Superhard alloys and ceramic materials. Superhard materials Preparation of superhard materials

Superhard materials

Superior materials - A group of substances possessing the highest hardness to which materials include the hardness and wear resistance of which exceeds the hardness and wear resistance of solid alloys based on tungsten carbides and titanium with a cobalt ligament of carbideotytan alloys on nickel-molybdenum bond. Widely used superhard materials: electrocorundum, zirconium oxide, silicon carbide, boron carbide, boron, diboride, diamond. Superior materials are often used as materials for abrasive processing.

In recent years, the close attention of the modern industry has been aimed at finding new types of superpower materials and assimilation of materials such as carbon nitride, boron-silicon nitride, Silicon nitride, Titan-carbide carbide alloy, boride alloys and carbide carbides with carbides and borides Lantanoids.


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Books

  • Instrumental materials in mechanical engineering: tutorial. Graph MO RF, Adskin AM .. The textbook presents materials for the manufacture of cutting, stamped, fitting, installation, auxiliary, instrumentation: instrumental, high-speed and ...

Tools are materials, the main purpose of which is to equip the working part of the tools. These include instrumental carbon, alloyed and high-speed steel, solid alloys, mineral cells, superhard materials.

The main properties of instrumental materials

Tool material Heat resistance 0 S. Tensile strength, MPa Micater and HV Heat-War Coefficient, W / (MTK)
Carbon steel

Alloy steel

Fasting Steel

Hard alloy

Mineralocheramic

Cubic nitride

8.1. Instrumental steel.

By chemical composition, doping degree Instrumental steel is divided into instrumental carbon, instrumental alloyed and high-speed steel. The physico-mechanical properties of these steels at normal temperatures are close enough, they differ in heat resistance and calcination with hardening.

In the instrumental alloyed steels, the mass content of alloying elements is not enough to bind the entire carbon in carbide, so the heat resistance of the steels of this group is only 50-100 0 s exceeds the heat resistance of tool carbon steels. In high-speed steel, they strive to associate the entire carbon in the carbides of alloying elements, eliminating the possibility of forming iron carbides. Due to this, the softening of high-speed steels occurs at higher temperatures.

Tool carbon (GOST 1435-74) and alloyed (GOST 5950-73) steel. The main physico-mechanical properties of tool carbon and alloyed steels are shown in the tables. Instrumental carbon steel are denoted by the letter in which a digit that characterizes the mass content of carbon in steel in tenths percentage. So, in steel grades U10, the mass content of carbon is one percent. The letter A in the designation corresponds to high-quality steels with a reduced mass content of impurities.

Chemical composition of carbonaceous instrumental steels

steel grade

steel grade

phosphorus - 0.035%, chromium - 0.2%

nickel - 0.25%, copper - 0.25%

Phosphorus - 0.03%, chromium - 0.15%

copper - 0.2%

In the instrumental alloyed steels, the first digit characterizes the mass content of carbon in the tenths of the percentage (if there is no digit, then the carbon content is in it to one percent). The letters in the designation indicate the content of the corresponding alloying elements: Mr. Manganese, x - chrome, C - silicon, in - tungsten, F - Vanadium, and the numbers indicate the content of the element in percent. Instrumental alloyed steel grades 9xc grades, clad, x, 11x, HBHs are distinguished by small deformations during thermal processing.

Chemical composition of lowered tool steels

steel grade

e. 0,4

e. 0,3

e. 0,35

e. 0,35

e. 0,35

e. 0,3

Notes:

  1. The chemical composition of the lowered steel B1 was installed so as to maintain the advantages of carbon steels, improving hardening and reducing the sensitivity to overheating.
  2. Steel type HP5 have an increased hardness (HRC to 70) due to the large content of carbon and reduced manganese content
  3. Chromium steel types X are treated with the steel of high calcination
  4. Steel doped with manganese type 9xc belong to resistant against reducing hardness upon vacation

These materials have limited applications: carbonistic go, mainly for the manufacture of plumbing tools, and doped - for thread-forming, woodworking and long-term tools (HUN) - broach, sweep, etc.

8.2. Filter steel (GOST 19265-73)

The chemical composition and the strength characteristics of the main stamps of these steels are shown in the tables. Filtering steel are denoted by letters corresponding to carbido-forming and alloying elements: R - Tungsten, M - Molybdenum, F - Vanadium, A - Nitrogen, K - Cobalt, T - Titanium, C - Zirconium). Behind the letter should be a digit that denotes the average mass content of the element in percent (chromium content of about 4 percent in the designation of the grades is not indicated).

The digit that stands at the beginning of the steel designation indicates the carbon content in tenths of the percent (for example, steel 11p3am3f2 contains about 1.1% C; 3% W; 3% Mo and 2% V). The cutting properties of high-speed steels are determined by the volume of the main carbido-forming elements: tungsten, molybdenum, vanadium and alloying elements, nitrogen. Vanadium due to low mass content (up to 3%) is usually not taken into account, and the cutting properties of steels are determined, as a rule, a tungsten equivalent equivalent (W + 2MO)%. In the price listings, three groups of steels are distinguished on high-speed steel: the 1st group with a tungsten equivalent of up to 16% without cobalt, the 2nd groups are up to 18% and the cobalt content of about 5%, 2st 0s of the 3rd group - up to 20% and cobalt content 5-10%. Accordingly, the cutting properties of these groups of steels differ.

Chemical composition of high-speed steels

steel grade

e. 0,5

e. 0,5

e. 0,5

e. 0,5

e. 0,5

Chemical composition of cast high-speed steels

steel grade

In addition to standard, special high-speed steel are used, containing, for example, titanium carbonitrides. However, the high hardness of the billets of these steels, the complexity of mechanical processing of non-widespread. When processing hard-productive materials, the use of powder high-speed steel P6M5-P and P6M5K5-P and P6M5K5-P The high cutting properties of these steels are determined by a special fine-grained structure that promotes strength to increase strength, a decrease in the radius of the cutting edge, improved cutting machinability and especially grinding. In the present time, industrial tests are launched with high-speed steel with an elevated content of various alloying elements, including aluminum, Malibden, nickel and other

One of the essential drawbacks of high-speed steels is associated with carbide inhomogeneity, i.e. With an uneven distribution of carbides in a section of the workpiece, which leads, in turn, to the uneven hardness of the cutting blade of the instrument and its wear. This disadvantage is absent in powder and martensite-aging (with a carbon content of less than 0.03%) of high-speed steels.

steel grade

Approximate appointment and technological features

It can be used for all types of cutting tools when processing conventional structural materials. It has high manufacturability.

Approximately for the same goals as steel P18. Worse grows.

For simple form tools that do not require a large amount of grinding operations; It is used to handle conventional structural materials; It has increased plasticity and can be used to make tools by plastic deformation methods; The graffugability is low.

For all types of cutting tools. It is possible to use for tools working with shock loads; Thicker than steel P18 temperatures interval, increased tendency to decarburization.

Cutting and receiving tools / shaped cutters, expanding, pulling, etc. / when processing structural steels.

The same as steel P6M5, but compared with Steel R6M has a slightly greater hardness and less durability.

Used for the manufacture of simple form tools that do not require a large amount of grinding operations are recommended for processing materials with elevated abrasive properties / fiberglass, plastics, ebony, etc. / for finishing tools working with average cutting rates and low cut sections; The graffugability is low.

For finishing and receiving tools working with medium cutting speeds; for materials with elevated abrasive properties; Recommended instead of steel R6F5 and P14F4, as steel than the best graffitability with approximately the same cutting properties.

R9m4K8, R6M5K5

For processing high-strength stainless steel, heat-resistant steels and alloys in conditions of increased heating of the cutting edge; The grainability is somewhat lowered.

P10K5F5, R12K5F5

For processing high-strength and hardware and alloys; materials with elevated abrasive properties; Low graffability.

For processing steels and alloys of increased hardness; finishing and obtaining processing without vibrations; The graffugability is low.

For a simple form tools when processing carbon and alloyed steels with strength not more than 800 MPa.

P6M5K5-MP, R9M4K8-MP (powder)

For the same purposes as R6M5K5 and P9M4K8; They have better grindability, less deformed during heat treatment, have greater durability, show more stable operational properties.

8.3. Solid alloys (GOST 3882-74)

Solid alloys contain a mixture of grains of carbides, nitrides, carbonitis of refractory metals in binding materials. Standard brands of solid alloys are based on tungsten carbides, titanium, tantalum. Cobalt is used as a bundle. The composition and main properties of some brands of solid alloys for cutting tools are shown in the table.

Physico-mechanical properties of single, two- and threecarbide solid alloys

The composition of the physico-mechanical properties of flavored solid alloys

Depending on the composition of the carbide phase and a liga, the designation of solid alloys includes letters characterizing carbido-forming elements (in - tungsten, T - titanium, the second letter T - tantalum) and the ligament (the letter K- cobalt). The mass fraction of carbidoid-forming elements in single-circular alloys containing only tungsten carbide is determined by the difference between 100% and mass fractions of the ligament (the number of the letter K), for example, the VK4 alloy contains 4% cobalt and 96% WC. Vioxicarbide WC + TIC alloys of the digit after the letter of the carbide-forming element determine the mass fraction of carbides of this element, the following digit is a mass fraction of a ligament, the rest is the mass fraction of tungsten carbide (for example, T5K10 alloy contains 5% TIC, 10% CO and 85% WC).

In threecarbide alloys, the digit after the letters TT means the mass fraction of Titan's carbides and tantalum. The figure of the letter K is a mass fraction of a ligament, the remaining mass fraction of tungsten carbide (for example, TT8K6 alloy contains 6% cobalt, 8% of titanium carbides and tantalum and 86% tungsten carbide).

In metalworking, the ISO standard highlighted three groups of carbide cutting tools: group P - for processing materials giving a drain chips; The group K is a chip chips and a group M - for processing various materials (universal solid alloys). Each area is divided into groups and subgroups.

Solid alloys are mainly produced in the form of various plates on the form and accuracy of the manufacture of plates: pruby (glued) - according to GOST 25393-82 or replaceable multifaceted - according to GOST 19043-80 - 19057-80 and other standards.

The multi-faceted plates are produced from both standard grades of solid alloys and from the same alloys with single-layer or multilayer super hard coatings from TiC, TIN, aluminum oxide and other chemical compounds. Plates with coatings have increased resistance. To the designation of plates from standard grades of solid alloys with titanium nitrides is added - marking kibe letters (TU 2-035-806-80), and to the designation of alloys by ISO - the letter C.

Plates and from special alloys are also available (for example, according to TU 48-19-308-80). Alloys of this group (MS groups) have higher cutting properties. The designation of the alloy consists of letters of MS and three-digit (for plates without coating) or a four-digit (for plates with titanium carbide) number:

The 1st digit of the designation corresponds to the application of the alloy using the ISO classification (1 - processing of materials that give a drain chips; 3 - processing of materials that give a chip of the dome; 2 - the processing area corresponding to the region of the ISO);

The 2nd and 3rd figures characterize the subgroup of the appliance, and the 4th digit - the presence of the coating. For example, MC111 (analogue of standard T15K6), MC1460 (analogue of standard T5K10), etc.

In addition to the finished plates, billets are also available in accordance with the OST 48-93-81; Designation of blanks is the same as the finished plates, but with the addition of the letter Z.

Outliframic solid alloys are widely used as materials that do not contain deficient elements. Roller alloys are supplied in the form of finished plates of various shapes and sizes, degrees of accuracy u and m, as well as blanks of plates. The applications of these alloys are similar to the areas of use of bicarbium solid alloys under unstressed loads.

It is applied for

Cleaning a small cross section of a cut, the final cutting of the thread, the deployment of holes and other similar types of processing of gray cast iron, non-ferrous metals and their alloys and non-metallic materials (rubber, fibers, plastics, glass, fiberglass, etc.). Cutting sheet glass

Finishing (sharpening, picking, cutting thread, deployment) of solid, alloyed and bleached iron, cemented and hardened steels, as well as highly abrasive non-metallic materials.

A roughing of the roughing with a non-uniform cross section of a cut-off and finvement milling, drilling and reservoiring of normal and deep holes, roughing centers in the processing of cast iron, non-ferrous metals and alloys, titanium and its alloys.

The finishing and beneficial processing of solid, alloyed and bleached iron, hardened steels and some stainless steel stainless steel stainless steel stainless steel and alloys, especially titanium-based alloys, tungsten and molybdenum (sharpening, retaching, deployment, thread cutting, shabby).

Increased processing of heat-resistant steels and alloys, stainless steels of austenitic class, special solid cast iron, hardened cast iron, solid bronze, light metal alloys, abrasive non-metallic materials, plastics, paper, glass. Processing hardened steels, as well as raw carbon and alloyed steels with thin cut sections on very low cutting speeds.

Cleaner and gaining, reassurance, milling and drilling gray and carpet cast iron, as well as bleached cast iron. Continuous sharpening with small cross sections of steel casting, high-strength, stainless steel, including hardened. Treatment of non-ferrous metal alloys and some brands of titanium alloys when cutting with small and medium cuts.

Black and receiving sharpening, pre-cutting of threads with turning cutters, obtaining milling of solid surfaces, drilling and reassurance of holes, the centers of gray cast iron, non-ferrous metals and their alloys and non-metallic materials.

Black current with a non-uniform cross section of cut and intermittent cutting, planing, black milling, drilling, rough drilling, roughing of gray cast iron, non-ferrous metals and their alloys and non-metallic materials. Processing stainless, high-strength and heat-resistant hardware and alloys, including titanium alloys.

Chernovaya and receiving treatment of solid, alloyed and bleached iron, some stainless steel stamps, high-strength and heat-resistant steels and alloys, especially titanium-based alloys, tungsten and molybdenum. Making some types of monolithic tools.

Drills, coinenings, deployments, milling and green-circuit of steel, cast iron, some hard-working materials and non-metals all-hard-solid, small-sized tool. Cutting tool for tree processing. Finishing with a small cross section of the cut (t of diamond processing); Cutting the threads and deploy openings of uncrowed and hardened carbon steels.

Having obtained sharpening with continuous cutting, finishing turning with intermittent cutting, cutting the thread with turning cutters and rotating heads, obtaining and finvey milling of solid surfaces, resulting in the pre-treated holes, finishing coinenings, deployment and other similar types of carbon and alloyed steels.

Roughing with a non-uniform cross section of a cut and continuous cutting, obtaining and finishing with intermittent cutting; rough milling of solid surfaces; Development of cast and forged holes, roughing coinenings and other similar types of carbon and alloyed steel treatments.

Roughing with a non-uniform cross section of a cut and intermittent cutting, shaped sharpening, cutting cutters; finishing planing; Black milling Intermittent surfaces and other types of carbon and alloyed steel treatments, mainly in the form of forgings, stamping and castings in crust and scale.

Heavy roughing for steel forgings, stamping and castings in a crust with sinks in the presence of sand, slag and various non-metallic inclusions, with a non-uniform cross section of a cut and presence. All types of planing of carbon and alloyed steels.

Heavy roughing of steel forgings, stamping and castings in crust with sinks with sand, slag and various non-metallic inclusions with a uniform cross section of the cut and presence of shock. All types of planing of carbon and alloyed steels. Heavy black milling and carbon and alloyed steels.

Chernovaya and gaining processing of some brands of difficult-to-material materials, stainless steels of austenitic class, malomagnetic steels and heat-resistant steels and alloys, including titanium.

Millingness of steel, especially milling of deep grooves and other types of processing that impose increased requirements for alloy resistance to thermal mechanical cyclic loads.

8.4. Mineralokermic (GOST 26630-75) and superhard materials

Mineralocheramic instrumental materials have high hardness, heat and wear resistance. Their base is alumina (silicon oxide) - oxide ceramics or a mixture of silicon oxide with carbides, nitrides and other connections (kermets). The main characteristics and scope of various brands of mineral cells are shown in the table. Forms and dimensions of replaceable multifaceted ceramic plates are defined by the standard GOST 25003-81 *.

In addition to traditional brands of oxide ceramics and Kermetov, oxide-nitride ceramics are widely used (for example, the ceramics of the Cortinite brand (a mixture of corundum or aluminum oxide with titanium nitride) and nitride-silicon ceramics- "Silinite-P".

Physical and mechanical properties of tool ceramics

Processed material

Hardness

Brand ceramics

Cast iron gray

VO-13, VSH-75, CM-332

Cast iron puffy

VSh-75, in-13

Cast iron bleached

Wok-60, ONT-20, B-3

Steel structural carbon

VO-13, VSH-75, CM-332

Stool construction alloying

VO-13, VSH-75, CM-332

Improved steel

VSh-75, VS-13, WK-60 Silinit-R

Steel cementated ordered

Wok-60, ONT-20, B-3

Wok-60, B-3, ONT-20

Copper alloys

Nickel alloys

Silinit-P, ONT-20

Synthetic superhard materials are manufactured either based on cubic nitride of boron - NBB, or on the basis of diamonds.

The materials of the KNB group have high hardness, wear resistance, low friction coefficient and iron inertia. Main characteristics and efficient use areas are shown in the table.

Physical and mechanical properties of STM based on the CNB

Recently, this group includes materials containing the Si-Al-O-N composition (Salon Trading Mark), which is based on Si3N4 silicon nitride.

Synthetic materials are supplied in the form of blanks or finished replaceable plates.

Based on synthetic diamonds, such brands are known as ASB - diamond synthetic "ballas", ASPC - diamond synthetic "carbonado" and others. The advantages of these materials are high chemical and corrosion resistance, minimal radii radios of blades and friction coefficient with the material being processed. However, diamonds have significant disadvantages: low bending strength (210-480 MPa); chemical activity to some fats contained in coolant; Dissolution in the gland at temperatures of 750-800 C, which practically eliminates the possibility of their use for processing steels and cast iron. Basically, polycrystalline artificial diamonds are used for the processing of aluminum, copper and alloys based on them.

Purpose of STM based on cubic nitride boron

Brand material

Application area

Composite 01 (Elbor r)

Slim and piston sharpness without impact and end milling of hardened steels and cast irons of any hardness, solid alloys (Co \u003d\u003e 15%)

Composite 03 (ISMIT)

Pure and getting processing of seasoned steels and castoffs of any hardness

Composite 05.

Preliminary and final sharpening steels (HRC e<= 55) и серого чугуна, торцовое фрезерование чугуна

Composite 06.

Celebration of seasoned steels (HRC e<= 63)

Composite 10 (hexanith r)

Preliminary and final strokes with impact and without impact, elder milling of steels and cast irons of any hardness, solid alloys (CO \u003d\u003e 15%), intermittent sharpness, processing of the deposited parts.

Chernot, obtained and finishing and milling of cast irons of any hardness, sharpening and reassurance of steels and copper-based alloys, cutting on casting crust

Composite 10d

Preliminary and final strokes, including with a blow, hardened steels and castoffs of any hardness, wear-resistant plasma surfacing, elder milling of hardened steels and cast iron.

Superhard materials (STM) - they include diamonds (natural and synthetic) and composite materials based on cubic boron nitride.

Diamond- One of the carbon modifications. Due to the cubic structure of the crystal lattice, the diamond is the most solid from the nature of minerals. Its hardness is 5 times higher than the solid alloy, however, the strength is small and natural diamond single crystals when critical loads achieve critical loads are destroyed into small fragments. Therefore, natural diamonds are used only on chisty operations for which small power loads are characteristic.

The heat resistance of diamonds is 700 ... 800 ° C (at higher diamond temperatures combustion). Natural diamonds have high thermal conductivity and the lowest friction coefficient.

Natural diamond denotes letter BUT , synthetic - AC . Natural diamonds are separate single crystals and their fragments, or threw crystals and aggregates. Synthetic diamonds are obtained in the form of fine-grained powders and used for the manufacture of abrasive circles, pastes and microphowers. A separate group consists of polycrystalline diamonds (PKA) stamps of ASB (Ballas) and ASPK (Carbonado). Due to its polycrystalline structure, due to its polycrystalline structure, significantly resist shock loads than diamond single crystals, and, despite the smaller hardness compared to a natural diamond, have higher values \u200b\u200bof tensile strength and transverse shift. The impact strength of diamond polycrystals depends on the size of diamond grains and with their increase decreases.

The diamond has a chemical affinity with nickel and iron-containing materials, so when cutting steels on the basis of iron, intensive sticking of the material being processed occurs on the contact surfaces of the diamond instrument. Carbon, from which the diamond consists, actively reacts with these materials when heated. This leads to intensive wear of the diamond tool and limits the areas of its use, therefore natural diamonds are used mainly with a thin sharp metal strip metal and alloys that do not contain carbon and iron. The most efficient use of diamond tools is obtained on finishing and finishing operations when processing parts from non-ferrous metals and their alloys, as well as from various polymer composite materials. The tool can be used in the accuracy of intermittent surfaces and during milling, however, its resistance will read than when processing without impact.

Processed material V, m / min s, mm / about T, mm.
Aluminum cast alloys 600…690 0,01…0,04 0,01…0,20
Aluminum magnesium alloys 390…500 0,01…0,05 0,01…0,20
Aluminum heat-resistant alloys 250…400 0,02…0,04 0,05…0,10
Duralumin 500…690 0,02…0,04 0,03…0,15
Bronze tiny 250…400 0,04…0,07 0,08…0,20
Bronze Leadsova 600…690 0,025...0,05 0,02…0,05
Brass 0,02…0,06 0,03…0,06
Titanium alloys 90…200 0,02…0,05 0,03…0,06
Plastics 90…200 0,02…0,05 0,05…0,15
Fibercistitol 600…690 0,02…0,05 0,03…0,05

In many cases, the large wear resistance of the cutters from synthetic diamonds, observed in practice, compared with the cutters from natural diamonds, which is explained by the difference in their structures. Natural diamond has cracks on the cutting edge, develop and can achieve significant sizes. In the PKA (synthetic diamond), the cracks arising are stopped by the boundaries of crystals, which determines their higher, in 1.5 ... 2.5 times, wear resistance.

Another of the promising areas of application of PKA is to process difficult to cut and causing rapid wear of the tool of materials such as chickens, high glue density plates, with melamine resin-based coatings, decorative paper-layered plastic, as well as other materials, Possessing abrasive action. The tool from the PKA has a resistance when processing such materials in 200..300 times higher than the durability of carbide tools.

Tools from PKA in the form of replaceable multi-faceted plates during the processing of polymer composite materials are successfully applied. Their use allows you to increase resistance to 15 ... 20 times compared to a solid alloy tool.

Cubic boron nitride(KNB, BN. ) It does not occur in nature, it is obtained by artificially from "white graphite" at high pressures and temperatures in the presence of catalysts. At the same time, the hexagonal grille of graphite turns into a cubic, similar to the diamond lattice. Each boron atom is connected to four nitrogen atoms. On the hardness of the KNB, the diamond is somewhat inferior, but has a higher heat resistance reaching up to 1300 ... 1500 ° C, and it is practically inert to carbon and iron. Like a diamond, the KNB has increased fragility and low bending strength.

Several brands of the KNB, combined into the "Composites" group. The varieties of the CNB differ from each other with dimensions, structure and properties of grains, percentage of ligaments, as well as sintering technology.

As composites, the most widespread use was found: composite 01 (elbor-p), composite 05, composite 10 (hexanite-p) and composite 10d (two-layer plates with a working layer of hexanite P). Of these, the most durable is composite 10 ( Σ I. \u003d 1000 ... 1500 MPa), so it is used at shock loads. The remaining composites are used in the unknown finishing processing of hardened steels, high-strength cast iron and some hard-processed alloys. In many cases, composites are more effective than grinding process, since due to its high thermal conductivity of the CNB does not give a licking when working at high cutting rates and provides low surface roughness.

Composites are used in the form of small-sized plates of square, triangular and round shapes fixed on the tool housing with soldering or mechanically. Recently, plates are used from solid alloy with a layer of composite or diamond polycrystals. Such multilayer plates have greater durability, wear resistance and more convenient for fastening. They allow you to remove the allowances of great depths.

The main reserve for improving the processing of tools based on BN. It is cutting speed (Table 11.), which can exceed the cutting speed by a carbide tool in 5 or more times.

Table 11. Cutting speeds allowed by various instrumental materials

The table shows that the greatest efficiency of the use of tools based on BN. Takes place when processing high-end cast iron, steels and alloys.

One of the opportunities to improve the effectiveness of a tool based on BN. is the use of lubricant liquids (coolant) that for tools from BN. Most effectively use by spraying when cutting speeds up to 90 ... 100 m / min.

Another of the effective areas of use of the tool equipped with composite polycrystals is the processing of the surfacing, which strengthen the parts of metallurgical production. The deposited materials of very high hardness (up to HRC 60..62) are obtained by electric arc or plasma-enclosure with powder wires or ribbons.

The scope of the cutting speed and submission of all groups of the considered instrumental materials is approximately shown in Fig. 38.

Fig.38. Scope of various tool material for cutting speed V. And feed s. .

1 - high-speed steel; 2 - solid alloys; 3 - solid alloys with coatings; 4 - nitride ceramics; 5 - oxide-carbide (black) ceramics; 6 - oxide ceramics; 7 - cubic nitride boron.

Metal processing processes with blade tools are subject to the classical laws of the theory of cutting metals.

On all over the development of metal processing with cutting the emergence of qualitatively new tool materials with increased hardness, heat resistance and wear resistance, was accompanied by an increase in the intensity of the processing process.

Created in our country and abroad at the end of the fifties, the beginning of the sixties of the last century and widely used tools equipped with artificial ultra-descendible materials based on cubic nitride boron (CNB) are characterized by a large variety.

According to domestic and foreign firms - manufacturers of instruments currently increase the use of materials based on the CNB.

In industrialized countries, the consumption of a blade tool made of artificial superterand materials based on the CNB continues to grow an average of up to 15% per year.

According to the classification proposed by VNIIINOinstrument, all over-vehicle materials based on dense modifications of Bora nitride are assigned the name of the composites.

In the theory and practice of materials science, the composite is called a material that is not found in nature, consisting of two and more different components on the chemical composition. For the composite, the presence of clear
Borders separating its components. The composite consists of filler and matrix. The greatest influence on its properties is the filler, depending on which the composites are divided into two groups: 1) with dispersed particles; 2) reinforced fiber reinforced fibers in several directions.

The thermodynamic features of Bora nitride polymorphism led to the appearance of a large number of materials based on its dense modifications and various technologies for its preparation.

Depending on the type of the main process flowing in the synthesis and the defining properties of superterald materials, in modern technologies of obtaining instrumental materials from boron nitride, three basic methods can be distinguished:

  • phase conversion of a boron hexagonal nitride into cubic. Polycrystalline superterand materials thus obtained differ from each other by the presence or absence of a catalyst, its type, structure, synthesis parameters, etc. The materials of this group include: composite 01 (Elbor-P) and composite 02 (Belbor). Abroad, the materials of this group are not produced;
  • partial or complete conversion of boron wurcite nitride into cubic. Separate materials of this group differ in the composition of the original mixture. In our country, from the materials of this group, one and two-layer composite 10 (hexanite-p) and various modifications of the composite 09 (PTNB, etc.) are produced. Abroad, the materials of this group are produced in Japan by the company "Nippon Oil Fate" under the trademark of Wurcyp;
  • sintering of particles of cubic boron nitride with additives. This group of materials is the most numerous, as various versions of the ligament and sintering technology are possible. According to this technology, a composite of 05 is produced in the domestic industry, kiborite and niborite. The most famous foreign materials are boron zones, amborite and sumboron.

We give a brief description of the most well-known superhard instrumental materials.

Composite 01. (Elbor-P) - created in the early 70s.

This material consists of randomly oriented cubic nitride boron crystals obtained by catalytic synthesis. As a result of high-temperature pressing under the action of high pressure, the initial BN K crystals are crushed to size 5 ... 20 microns. The physicomechanical properties of the composite 01 depend on the composition of the original mixture and thermodynamic parameters of synthesis (pressure, temperature, time). An exemplary mass content of the components of the composite 01 is as follows: up to 92% Bn k, up to 3% BN R, the rest is the impurities of the add-on-catalysts.

The modification of the composite 01 (Elbor-PM), in contrast to ELORB-P, is obtained by direct synthesis BN R -\u003e Bn to, carried out at high pressures (4.0 ... 7.5 GPa) and temperatures (1300 ... 2000 ° C). The absence of a catalyst in the mixture allows you to get stable operational properties.

Composite 02. (Belbor) - created at the Institute of Solid State Physics and Semiconductors of the BCSR Academy of Sciences.

It turns out a direct transition from BN R in high pressure apparatus with a static load application (pressure up to 9 GPa, temperature up to 2900 ° C). The process is carried out without a catalyst, which ensures high physicomechanical properties of the composite 02. With a simplified manufacturing technology, due to the introduction of certain alloying additives, it is possible to vary the physicomechanical properties of polycrystals.

Belbor on hardness is comparable with a diamond and significantly surpasses it in heat resistance. Unlike diamond, it is chemically inert to the gland, and this makes it possible to effectively use it for the processing of cast iron and steels - the main machine-building materials.

Composite 03. (ISMIT) - for the first time synthesized in the ISS of the USSR Academy of Sciences.

Three material grades are produced: Ismite-1, Ismite-2, Ismite-3, differing by physicomechanical and operational properties, which is a consequence of the difference in the raw materials and synthesis parameters.

Niborith - Received IFVD Academy of Sciences of the USSR.

High solidness, heat resistance and significant sizes of these polycrystals predetermine their high performance properties.

Kiborit - It is synthesized for the first time in the ISS of the USSR Academy of Sciences.

Polycrystals are obtained by hot pressing of the mixture (sintering) at high static pressures. The composition of the mixture includes a boron cubic nitride powder and special activating additives. The composition and the number of additives, as well as the sintering conditions ensure the preparation of a structure in which the struck the BN crystals form a continuous frame (matrix). In the interstal intervals of the frame formed by refractory hard ceramics.

Composite 05. - The structure and technology of obtaining are developed at NPO VNIIAS.

The material based on boron cubic nitride crystals (85 ... 95%) sintered at high pressures with additives of aluminum oxide, diamonds, etc. elements. In terms of its physicomechanical properties, composite 05 is inferior to many polycrystalline ultra-read materials.

Modification of the composite 05 is composite 05IT. It is characterized by high thermal conductivity and heat resistance, which are obtained by introducing special additives in the mixture.

Composite 09. (PTNB) developed at the Institute of Chemical Physics of the Academy of Sciences of the USSR.

Several brands (PTNB-5MK, PTNB-IR-1, etc.) are produced, which differ in the composition of the initial charge (mixture of BN B and BN powders). The difference between the composite 09 from other composite materials is that it is the basis of the boron cubic nitride particles with dimensions of 3 ... 5 μm, and Wurcitic boron nitride acts as a filler.

Abroad, the production of materials of this class using the transformation of the Wurcite nitride boron is carried out in Japan "Nippon Oil Fate" together with the Tokyo State University.

Composite 10. (Hexanit-p) was established in 1972 by the Institute for Materials Sciences of the USSR Academy of Sciences together with the Poltava plant of artificial diamonds and diamond instruments.

This is a polycrystalline superterand material, the basis of which is a wurzit modification of boron nitride. The technological process of obtaining hexanite-P, as well as the previous composites, consists of two operations:

  1. bN B synthesis by the method of direct transition BN R -\u003e BN in with shock exposure to the source material and
  2. sintering BN powder at high pressures and temperatures.

For composite 10, a fine-grained structure is characteristic, but the dimensions of the crystals can vary in significant limits. The features of the structure are determined by the special mechanical properties of the composite 10 - it not only has high cutting properties, but also can successfully work at shock loads, which is less pronounced in other brands of composites.

On the basis of hexanite-p at the Institute of Problems of Materials Sciences of the Academy of Sciences of the Ukrainian SSR, an improved brand of composite composite 10 - hexanite-ral, reinforced with filamentous crystals - Sapphire Mustov fibers.

Composite 12. It is obtained by sintering at high pressures of the mixture of wuracite nitride boron powder and polycrystalline particles based on Si 3 N 4 (silicon nitride). The size of the grain of the main phase of the composite does not exceed 0.5 μm.

The prospect of further development, the creation and production of composites is associated with the use of threaded or needle-shaped crystals (musty), which can be obtained from materials such as in 4 C, SiC, Si 2 N 4. Veo and others.

One of the directions of improving the cutting properties of tools, allowing to increase productivity during machining, is to increase the hardness and heat resistance of instrumental materials. The most promising in this respect is diamond and synthetic superhard materials based on boron nitride.

Diamonds and diamond instruments Widely used in the processing of parts from various materials. For diamonds, exceptionally high hardness and wear resistance are characteristic. According to the absolute hardness of the diamond 4 - 5 times the hardness of solid alloys and in tens and hundreds of times the wear resistance of other instrumental materials in the processing of color alloys and plastics. In addition, due to the high thermal conductivity of diamonds, heat from the cutting zone is better, which contributes to the guaranteed receipt of parts with a non-violent surface. However, diamonds are very fragile, which strongly narrows the scope of their application.

For the manufacture of cutting tools, the main use received artificial diamondswhich in their properties is close to natural. At high pressures and temperatures in artificial diamonds, it is possible to obtain the same arrangement of carbon atoms as in natural ones. The mass of one artificial diamond is usually 1/8-1 / 10 carats (1 carat - 0.2 g). Due to the smallness of the dimensions of artificial crystals, they are unsuitable for the manufacture of such tools, such as drills, cutters and others, and therefore are used in the manufacture of powders for diamond grinding wheels and triwort pastes.

Blade diamond instruments Produced on the basis of polycrystalline materials like "Carbonado" or "Ballas". These tools have a long dimensional resistance periods and provide high quality treated surface. They are used in the processing of titanium, highly end aluminum alloys, fiberglass and plastics, solid alloys and other materials.

Diamond as instrumental material has a significant drawback - at elevated temperature, it enters into a chemical reaction with iron and loses performance.

In order to handle steel, cast iron and other iron-based materials were created superhard materials, chemically inert to it. Such materials were obtained by technology close to diamond production technology, but not graphite, but boron nitride, is used as a starting material.

The polycrystals of dense modifications of boron nitride are superior to heat resistance all materials used for the blade tool: diamond 1.9 times, high-speed steel 2.3 times, solid alloy 1.7 times, mineral cells 1.2 times.

These materials are isotropic (the same strength in various directions), has a microhardness of a smaller, but close to the hardness of the diamond, increased heat resistance, high thermal conductivity and chemical inertness with respect to carbon and iron.

The characteristics of the individuals of the materials under consideration, which are currently called the "composite", are shown in the table.

Comparative characteristics of STM based on boron nitride

Mark. Initial title HV Hardness, GPU Heat resistance, o with
Composite 01. Elbor-R. 60...80 1100...1300
Composite 02. Belbor. 60...90 900...1000
Composite 03. Ismith 60 1000
Composite 05. Composite 70 1000
Composite 09. PKNB 60...90 1500
Composite 10. Hexanit-R. 50...60 750...850

The effectiveness of the use of blade tools from various stamps of composites is related to the improvement of the design of the tools and the manufacturing technology and with the definition of the rational area of \u200b\u200btheir use:

    composites 01 (Elbor-R) and 02 (Belbor) Used for thin and finishing and milling without blows of parts from hardened steels with hardness 55 ... 70 HRC, cast iron and solid alloys VK15, VK20 and VK25 with supplies up to 0.20 mm / respectively and depth cutting to 0.8
    composite 05.apply for a clean and obtained sharpening without blows of parts from hardened steels with a hardness of 40 ... 58 HRC, cast iron hardness up to 300 HV with feeds up to 0.25 mm / respectively and a depth of 2.5 mm
    composite 10 (hexanite-p) Used for thin, finishing and obtaining and milling with blows of parts from hardened steels hardness not higher than 58 HRC, castoffs of any hardness, alloys VK15, VK20, VK25 with a supply of up to 0.15 mm / o and depth of cutting to 0.6 mm

At the same time, the period of resistance of tools increases in tens of times compared with other instrumental materials.