RU2800345C1 - Mixed cutting ceramics and method for manufacturing cutting plates from mixed cutting ceramics - Google Patents

Abstract

FIELD: powder metallurgy.

SUBSTANCE: cutting tools for processing hard-to-cut steels and alloys, as well as high-strength and grey cast iron on machine tools. Mixed cutting ceramics contains, wt.%: aluminium oxide - 27-30, silicon oxide SiO₂ - 27-31, tantalum carbide TaC - 9-10, titanium carbide TiC - 23-24, tungsten carbide WC - 9-10. A mixture of silicon oxide and aluminium oxide is calcined at a temperature of 1750-1760°C, subjected to fine vibrogrinding on a vibratory unit for 3.5-4.5 hours and dried. After drying, titanium carbide, tantalum carbide, tungsten carbide are introduced and mixed until they are uniformly distributed over the volume and an aqueous suspension is formed, into which deoxidizing catalyst additives are introduced in the form of magnesium oxide MgO, calcium oxide CaO, sodium oxide Na₂O, and subjected to spray drying to obtain a mixture. The resulting mixture is pressed to form a cutting plate, sintered at 3870-3950°C and subjected to short-term annealing with an exposure of 10.0-15.0 minutes at a temperature of 1650-1680°C. After annealing, machining is carried out to obtain a roughness of the faces equal to 0.06-0.08 mcm.

EFFECT: increased intergranular corrosion resistance, thermal wear resistance, ductility, impact strength and workability of plates, yield strength during hot pressing and sintering of plates, strength and hardness.

2 cl, 1 tbl

Description

The invention relates to the manufacture of superhard, high-strength, wear-resistant ceramic plates for equipping cutting tools for processing hard-to-cut steels and alloys, as well as high-strength white and gray cast irons SCH18, SCH20, etc., on metalworking machines.

Known (GOSTs for cutting ceramics VOK-60 GOST 25003-81; VOK-63, V-3, VOK-73 GOST19043-80).

Known (see Puchkin V.N., Kornienko V.G., Kononenko T.V. “Increasing technological conditions on CNC machines during turning (methodology). Monograph Published by FGBOU VO “KubGTU”, Krasnodar. 2014, p. 173) produced domestic oxide-carbide cutting ceramics of the grades VOK-60, VOK-63, V-3, VOK- 73 (mixed, "metallic", "black") ceramics, consisting of Al ₂ 0 ₃ oxide (up to 60%), TiC (up to 20-40%), Zr02 (up to 20-40%) and other refractory metal carbides with some alloying additions. Oxide-carbide ceramic plates are produced by hot pressing in graphite molds.

The production of plates begins with the grinding of the components of the mixture and the preparation of the charge. Then, mixing of the components, wet grinding of the prepared mixture, drying, dosing and hot pressing are performed. Having finished pressing, the mold is dismantled, the pressed blanks are taken out and transferred to mechanical processing.

The quality and stability of the cutting inserts are largely determined by the following factors: the content of titanium carbide and aluminum oxide in the initial charge, the grinding time of the mixture, the temperature and holding time during hot pressing, and the pressing pressure.

Insert hardness as delivered, HRA 92...94.

The resistance of inserts at the stage of delivery when cutting hard-to-cut and heat-resistant steels of grades 12X18H10T, 14X17H2, etc. - 60 min.

Mechanical properties of the plates as delivered: bending stress _σu = 600 MPa; density 4.2 g/cm ³ ; grain size 2...3 microns; hardness HRA 92…94.

A known method for producing a ceramic plate for a cutting tool (see patent RU No. 2699434 C1, IPC C22C 29/12, B22F 3/16, B23B 27/14, publ. 09/05/2019), including calcination of alumina containing α-A1 ₂ O ₃ and γ-A1 ₂ O ₃ , its vibroism grinding, enrichment, drying to obtain aluminum oxide of the α-Al ₂ O ₃ modification, its mixing with silicon oxide, titanium carbide, tungsten carbide, chromium oxide, nickel, molybdenum, niobium and cobalt, plasticization and hot pressing to obtain a pressed plate, sintering, annealing with exposure for 5-10 minutes in the region of the temperature maximum and its mechanical processing.

A known method for producing a ceramic insert for a cutting tool (see patent RU No. 2679264, IPC B23B 27/14, B22F 3/15, C22C 29/12, publ. 06.02.2019), including calcination of alumina, its vibrogrinding, enrichment, drying to obtain alumina modification α-Al ₂ O ₃ . The resulting aluminum oxide is mixed with alloying components in the following ratio, wt.%: aluminum oxide 58-60, titanium carbide 30-32, chromium oxide 5-7, nickel 2-3, molybdenum 1-2. Next, plasticization and hot pressing are carried out to obtain a pressed plate, sintering and annealing with an exposure of 5-10 minutes in the region of the temperature maximum of the obtained plate and its mechanical processing.

Known plates of oxide-carbide cutting ceramic grades VOK-60, VOK-63, VOK-73, VO-3, etc., produced by our domestic industry VOK-60 GOST 25003-81 [http://docs.cntd.ru/document/1200009570]; VOK-71 GOST19043-80 (V.P. Zhed, G.V. Borovsky, Ya.A. Muzykant, G.M. Ippolitov "Cutting tools equipped with superhard and ceramic materials, and their application: Handbook" Mechanical Engineering, 1987, 320 pp.).

The closest technical solution is oxide-carbide cutting ceramics VOK-60, consisting of aluminum oxide A1 ₂ O ₃ (up to 60%), TiC (up to 20%), ZrO ₂ (up to 20%) with some MgO and ZrO ₂ alloying additives. The starting material for the production of oxide and oxide-carbide ceramics in the Russian Federation is technical alumina, which is a mixture of two modifications: γ - A1 ₂ O ₃ with a density of 3.65 g / cm ³ and α - A1 ₂ 0 ₃ with a density of 3.96 g / cm ³ (see V.P. Zhed, G.V. Borovsky, Ya.A. Muzykant, G.M. Ippolitov “Rezh Power tools equipped with superhard and ceramic materials and their application: Handbook "Mashinostroenie, 1987, pp. 15 - 22).

The disadvantage of oxide-carbide cutting ceramics based on aluminum oxide is brittleness, low wear and corrosion resistance, temperature resistance, and low resistance of inserts, especially when machining hard-to-cut steels, alloys and materials.

The closest technical solution is a method of manufacturing cutting ceramics (see ibid.), where plates of oxide-carbide mixed ceramics are obtained by hot pressing in graphite molds. The plates are used for processing malleable, chilled cast irons, heat-treated, case-hardened and hardened to HRC 30 ... 65 steels (see Table 1.4).

The main disadvantages of the method are:

1. This process is more laborious than the process of obtaining oxide ceramics.

2. The inserts are used for processing malleable, chilled cast irons, heat-treated, case-hardened and hardened to HRC 30…65 steels.

3. The hardness of the plates obtained by this method is 94HRA, the hardness of the RK we offer is 99 HRA.

4 The durability of RC VOK-60 T = 25...30 min, when processing hard-to-cut steels of grade 12X18N9T, the resistance of the RC we offer is T = 180…185 min.

5. The stress of the RC VOK-60 σ _in = 600 MPa, in the RC we offer σ _in = 990 MPa

The technical result of the proposed solution is:

– increase in intergranular corrosion resistance, thermal wear resistance, plasticity, impact strength and performance of plates made of oxide-carbide titanium-tantalum-tungsten cutting ceramics OK60TTVRK40;

– increasing the yield strength during hot pressing and sintering of plates;

− increasing the strength and hardness of the plates.

The essence of the invention lies in the fact that the mixed cutting ceramic containing aluminum oxide, silicon oxide, additionally contains titanium carbide, tantalum carbide, tungsten carbide in the following ratio, wt.%:

aluminum oxide Al ₂ O ₃ 27 - 30 silicon oxide SiO ₂ 27 - 31 tantalum carbide TaC 9 - 10 titanium carbide TiC 23 - 24 tungsten carbide WC 9 - 10

A method for manufacturing a cutting insert from mixed cutting ceramics, characterized in that a mixture of silicon oxide, aluminum oxide, is calcined at a temperature of 1750 - 1760 ° C, subjected to fine vibrogrinding in a vibrating unit for 3.5 ... before their uniform distribution over the volume and the formation of an aqueous suspension, deoxidizing additives of catalysts in the form of magnesium oxide MgO, calcium oxide CaO, sodium oxide Na₂O, and they are sprayed drying with the mixture, after which the resulting mixture is pressed with the formation of a cutting plate, subjected to a temperature of 3870 ... 3950 ° C and short-term annealing with an exposure of 10.0-15.0 minutes at a temperature of 1650-1680 ° C, and special processing plates with the production of roughness are subjected to 0, equal, equal to 0, equal, equal 06-0.08 μm.

The catalysts used in the process of sintering the plates and their presence in this case contributes to the sintering of the alloy of this plate, since titanium, tantalum and tungsten carbides are refractory and when sintered at a high temperature T = 3800°C. For reference, titanium carbide TiC has a melting point T = 3140°C, tantalum carbide TaC has a melting point T = 3800°C, tungsten carbide WC has a melting point of 2600°C. Therefore, a rational sintering temperature T = 3800°C was chosen, as well as to refine the grain size of the alloy structure of the plates and reduce the grain of the alloy to improve the mechanical properties of the plates, sintering is carried out with the presence of calcium oxide, sodium oxide, magnesium oxide catalysts.

A method of manufacturing oxide-carbide titanium-tantalum-tungsten cutting ceramics OK60TTVRK40 containing silicon oxide, aluminum oxide, silicon oxide, calcined at a temperature of 1750 - 1760 ° C, subjected to fine vibrogrinding in a vibrating unit for 3.5 ... 4.5 hours and dried, after drying, titanium carbides are added to the main composition , tantalum, tungsten, and mixing is carried out until the additives are evenly distributed by volume and a suspension is formed, which, after the introduction of deoxidizing additives of catalysts of magnesium oxide MgO, calcium oxide CaO, sodium oxide Na₂O, to improve the sinterability of the alloy during pressing, it is subjected to spray drying, then cutting plates are pressed from the mixture obtained, sintering is carried out at a temperature of 3870 ... µm.

Characteristics of chemical components :

Aluminum oxide Al ₂ O ₃ up to 30%, - molecular weight M = 101.96; B / c, density ρ \u003d 3.96 G / cm ² ; melting temperature t _pl =2050°C; phase shift temperature α→β , 573°С, standard molar heat capacity \u003d 79.04 J × mol- ¹ × K ^-1 , standard; molar entropy S ⁰ = 50.92 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H - 113 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G = 1582 kJ × mol ^-1 , molar enthalpy of fusion Δ H _melt = 113 kJ × mol ^-1 does not dissolve in H ₂ O (in water).

Silicon oxide SiO ₂ ≥ 30%; - molecular weight M = 60.08; B / c, density ρ \u003d 2.651 G / cm ² ; melting temperature t _pl =1610°C; phase shift temperature α→β , 573°С, standard molar heat capacity =44.43 J × mol ^-1 × K ^-1 standard; molar entropy S ⁰ = 41.84 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H - 908.3 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G = -856.7 kJ × mol ^-1 , molar enthalpy of fusion Δ H _melt = 8.54 kJ × mol ^-1 not solution yasya in H ₂ O (in water), react. HF.

Titanium carbide TiC ≥ 20% - molecular weight M = 59.91; gray color, density ρ = 4.92 G/ ^cm2 ; melting temperature t _pl ≈ 3140°С; boiling point _tbp ≈ 4300°C, standard molar heat capacity \u003d 34.30 J × mol ^-1 × K ^-1 , standard molar entropy S ⁰ \u003d 30.3 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H ⁰ \u003d - 209 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G \u003d - 294.4 kJ × mol ^-1 , does not dissolve in H ₂ O ( in water) and in HCl acids. H ₂ SO ₄ , reacts with HNO ₃ + HF, melts with alkali.

Tungsten carbide WC ≥ 10% - molecular weight M = 195.86; gray-blue color, density ρ = 15.7 G/cm ² ; melting temperature t _pl = 2600°C; standard molar heat capacity = 35.10 J × mol ^-1 × ^{k -1} , standard molar ^{entropy S 0} = 35 J × _mol ^-1 × k ^-1 , standard molar enthalpia

Tantalum carbide TaC ≥ 10% - molecular weight M = 192.96; yellow color of gold, density ρ = 14.4 G/cm ² ; melting temperature t _pl = 3800°C; boiling point _tbp ≈ 5500°C; standard molar heat capacity \u003d 36.8 J × mol ^-1 × K ^-1 , standard molar entropy S ⁰ \u003d 42.34 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H ⁰ - 141.8 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G \u003d - 140.4 kJ × mol-1, does not dissolve in H ₂ O (in water), slow Reag. HF, H ₂ SO ₄ , reactive. with HF + HNO ₃ .

Sodium oxide Na ₂ O ≥ 3%; - molecular weight M = 61.98; B / c, density ρ \u003d 2.27 G / cm ² ; standard molar heat capacity = -377 J × mol ^-1 × K ^-1 , standard; molar entropy S ⁰ = 75.3 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H - 415 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G = -377 kJ × mol ^-1 , reag. with water H ₂ O.

Magnesium oxide MgO ≥ 3%; - molecular weight M = 40.3; B / c, density ρ \u003d 3.58 G / cm ² ; melting temperature t _pl =2825°C; boiling point t _bale =3600°C; standard molar heat capacity = 37.2 J × mol ^-1 × K ^-1 standard; molar entropy S ⁰ = 27.1 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H - 601.5 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G = -567 kJ × mol ^-1 , reactive in NH ₄ salts, reactive. with acids.

Calcium oxide CaO ≥ 1%; molecular weight M = 56.08; B / c, density ρ \u003d 3.4 G / cm ² ; melting temperature t _pl =2600°C; boiling point t _bale =2850°C; standard molar heat capacity = 42 J × mol ^-1 × K ^-1 standard; molar entropy S ⁰ = 38.1 J × mol ^-1 × K ^-1 , standard molar enthalpy of formation Δ H - 635 kJ × mol ^-1 , standard molar Gibbs energy of formation Δ G = -604.2 kJ × mol ^-1 , reag. with acids.

Consider an example of plate manufacturing.

The technological process of manufacturing the proposed composition of plates of oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40.

The production of plates from oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40, to equip the cutting tool is carried out as follows:

Raw materials for the manufacture of plates from oxide-carbide titanium-tantalum-tungsten cutting ceramic grade OK60TTVRK40 are tested according to the following technology, which determines:

- chemical purity (contamination of alumina with Na ₂ O, CaO compounds is unacceptable);

- humidity;

is the surface area of the grains, which characterizes the activity of the material during sintering and makes it possible to estimate the expected graininess;

– compressibility (determined by the conditions of alumina processing);

– control of plate sintering density;

– control of graininess of plates.

The selection of raw materials for the method of obtaining plates from mixed cutting ceramics of a new chemical composition of the brand OK60TTVRK40 is carried out according to the following criteria for the chemical purity of alumina consisting of aluminum oxide Al ₂ O ₃ , silicon oxide SiO ₂ , since unacceptable oxides Na2O, CaO can get from alumina). In addition, the selection of alumina Na2O, CaO is carried out according to humidity, which is also unacceptable, since it affects the sintering of the plates. An important factor is the grinding of alumina, silicon nitride Si3N4 and cobalt oxide CoO to 0.8 ... 1.2 microns. The surface area of the grain of chemical compounds in order to obtain a fine-grained structure of the crystal lattice of pressed plates from cutting ceramics of a new composition, which is also one of the important criteria, (i.e., the graininess of the RC). Grain also affects the density of the plates and is one of the important indicators. The higher the density, the smaller the grain and the better the structure of the crystal lattice of the plate, which affects the basic mechanical properties of cutting ceramic plates during their operation (especially when cutting hard-to-cut steel grade 12Kh18N9T).

Then carry out the preparation of the charge.

Using a dispenser and an analytical balance, we add to the main composition, which consists of silicon oxide (SiO₂, aluminum oxide Al₂O₃, as a percentage of small amounts of chemical compounds titanium carbide TiC, tantalum carbide TaC, tungsten carbide WC, which contribute to the formation of hardening phases, increase the hardness, performance and wear resistance of the inserts when machining hard-to-cut materials and steel grades 12X18H9T, 14X17H2, and resistance to tempering, heat resistance and corrosion resistance, impact strength, ductility of the plates, and also facilitate sintering plates and inhibiting the growth of grains. With thorough mixing of this "mass" in the mixer, these additives are evenly distributed throughout the volume; an aqueous suspension is obtained, which, after the introduction deoxidizing additives catalysts magnesium oxide MgO, calcium oxide CaO, sodium oxide Na₂O, to improve the sinterability of the alloy during pressing, it is subjected to spray drying.

The resulting mass is controlled: chemical purity; workability; density; the average grain diameter, which should correspond to the arithmetic mean value not exceeding 1.0 µm.

After control with positive results, you can start pressing the cutting plates and subsequent hot sintering.

The main composition, which consists of silicon oxide SiO ₂ ≥ 30%, aluminum oxide Al ₂ O ₃ ≥ 30%, is calcined to 1720-1780 ° C and subjected to fine vibrogrinding in a vibratory unit for 3.5-4.5 hours (the time required for grinding the mass of the composition) to obtain particles with a size of 0.8 ... 1.0 μm (up to 90 ... 95% in the main mass) at a maximum particle size of 1.0 μm (during this time, the particles of the mass are crushed to a size of 1.0 μm).

The resulting mass is enriched and dried.

If you go beyond the specified rational temperatures of 1720-1780 ° C, there will be a change in the crystal structure of the plates, grain growth in the alloy will occur, which will lead to chipping of the plates, cracks and brittleness of the plates and their blunting during testing, when cutting hard-to-cut materials and steel grades 12X18H9T, 14X17H2, as well as sticking of molten metal to the workpiece, which degrades the quality and precision of the workpiece. This reduces the durability of the cutting tool, equipped with plates of oxide-carbide titanium-tantalum-tungsten cutting ceramic grade OK60TTVRK40.

Then the plasticization and hot pressing of the plates is carried out, from the resulting mixture.

Pressed plates are sintered from oxide-carbide titanium-tantalum-tungsten cutting ceramic grade OK60TTVRK40, at a temperature of 3880-3950°C and a short-term annealing mode with an exposure of 10.0-15.0 min at a temperature of 1620-1680°C.

Due to the fact that the indicated melting and boiling points are high for chemical compounds (carbides) in solution, rational temperature conditions are used for pressing and sintering plates

The sintering density of the plates and the grain size of the plates are controlled.

In conclusion, the plates are machined to obtain the roughness of the faces Ra = 0.06-0.08 µm.

As a result of the development and manufacture of high-strength plates from oxide-carbide titanium-tantalum-tungsten cutting ceramics of the brand OK60TTVRK40 of a new chemical composition, the following result is achieved for equipping the cutting tool:

– increased intergranular corrosion resistance, thermal wear resistance, ductility, impact strength and performance of plates made of oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40 by 3.35 times;

– increases the yield strength by 1.65 times and increases the strength and hardness of the plates by 1.35 times;

– improved physical and chemical properties of oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40 of a new chemical composition compared to oxide-carbide RK grade VOK-60, produced by our domestic industry and foreign;

– increased resistance of oxide-carbide titanium-tantalum-tungsten cutting ceramics brand OK60TTVRK40 of a new chemical composition, when cutting hard-to-cut steels of grades 12X18H10T, 40X13, 14X17H2 and alloys, as well as high-strength and gray cast irons SCH18, SCH20, etc., up to 185 min compared to oxide but-carbide RK grade VOK-60, produced by our domestic industry, which is no more than 25-30 minutes, depending on the cutting conditions;

– the temperature regimes of cutting were established during the processing of hard-to-cut materials and steels 12Kh18N10T, 40Kh13, 14Kh17N2 and alloys, as well as high-strength and gray cast irons SCH18, SCH20, etc., and the thermodynamic regularities of the modes of this process; the range of cutting temperatures in the cutting zone during the processing of hard-to-cut steels "blank-tool" to 680°С is extended, at which the cutting properties of the tool equipped with oxide-carbide titanium-tantalum-tungsten cutting ceramics of the brand OK60TTVRK40 of a new chemical composition are preserved, while the quality and accuracy of the workpiece do not deteriorate and the cutting tool does not become dull during cutting;

– Rational cutting conditions are determined, in which the wear resistance of RI, equipped with plates of oxide-carbide titanium-tantalum-tungsten cutting ceramic brand OK60TTVRK40 of a new chemical composition, when processing hard-to-cut, heat-resistant steels using a new LC with additives according to the KubGTU patent No. 2101333 with the following mass composition: formic acid 12…1 3%; maleic acid 8…9%; fumaric acid 7…8%; succinic acid 8…9%; furanones 35 ... 36%, the rest - water, will be maximum.

For experimental verification of the proposed plates from oxide-carbide titanium-tantalum-tungsten cutting ceramic brand OK60TTVRK40 of a new chemical composition, standard samples of plates with a size of 10 × 10 × 4.5 mm were made to equip cutters.

Then the shafts were machined from hard-to-cut steel grade 12Kh18N10T ∅50 to a length of 100 mm with cutters equipped with oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40 and cutters equipped with oxide-carbide cutting ceramics grade VOK-60 based on oxide and aluminium.

At the same time, the durability of cutters equipped with plates made of oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40 was 175...185 min, and cutters equipped with plates made of oxide-carbide cutting ceramics grade VOK-60 based on aluminum oxide was 35...43 min. THAT. the durability of the cutters equipped with plates made of oxide-carbide titanium-tantalum-tungsten cutting ceramic grade OK60TTVRK40 was approximately 4.14 times higher than the cutters equipped with plates made of oxide-carbide cutting ceramic grade VOK-60 based on aluminum oxide.

This development and manufacture of plates from oxide-carbide titanium-tantalum-tungsten cutting ceramic grade OK60TTVRK40 of a new chemical composition Al₂O₃ ≥ 30% SiO₂ ≥ 30%, ТiC ≥ 20%; TaC ≥ 10%; WC ≥ 10%; for equipping cutting tools, it was introduced at MAPP LLC (Limited Liability Company Mechanization, Automation of Production Processes), when processing shafts from hard-to-cut steels 12X18H10T and 14X17H2. The use of plates made of oxide-carbide titanium-tantalum-tungsten cutting ceramic grade OK60TTVRK40, when processing shafts, increased the quality and accuracy of the machined parts, which satisfies the technical and consumer properties of the products. The productivity of mechanical processing of shafts has increased, which has resulted in savings at the MAPP LLC enterprise Limited Liability Company Mechanization, automation of production processes, during the processing of shafts made of hard-to-cut steel 12X18H10T. The use of plates made of oxide-carbide titanium-tantalum-tungsten cutting ceramics grade OK60TTVRK40, when processing shafts, increased the quality and accuracy of the machined parts, which satisfies the technical and consumer properties of the products. The productivity of mechanical processing of shafts has increased, which has saved 200 thousand rubles at the MAPP LLC enterprise. compared with the use of hard-alloy tungsten-containing RI grades R6M5, R9, R18. Also, plates of oxide-carbide-dantalo-wolframa cutting ceramics of the OK60TTVRK40 brand, for equipping the RI, during the processing of shafts and gears of the hard-to-hardened steels 12x18N10, 14x17N2 and the Gray Cast iron at the Armavir Electromechanical Plant, are introduced. . rub.

The compositions of raw materials for the manufacture of plates and the physical and mechanical properties of the products are presented in the table.

Table

Compositions of raw materials for the manufacture of plates from RK and their chemical and mechanical properties

No.
Composition
RK aluminum oxide
nia Oxide
silicon carbide
tantalum carbide
titanium carbide
vol-
form Tver-
dost
HRA stamina,
min Bending stress
MPa Compressive stress Density
g/ ^cm3 Grain size µm 1 26 31 eleven 22 10 96 60-90 600 4900 5.5 2 2 27 31 10 23 9 97 100-120 800 5000 6.2 1.5 3 28 28 10 24 10 98.8 170-180 950 5100 7.75 0.9 4 thirty 27 9 24 10 98.5 150-170 980 5000 7.65 1.2 5 31 26 8 26 9 99 175-185 990 5250 5.4 0.8…1.0 Most
close analogue
* 60 - - 40 - 94 25 - 30 600 4800 4.2 2...3

* - oxide-carbide cutting ceramics VOK-60 (see V.P. Zhed, G.V. Borovsky, Ya * A. Muzykant, G. M. Ippolitov “Cutting tools equipped with superhard and ceramic materials, and their application: Handbook” Mechanical engineering, 1987, 320 pp.) pp. 15-22.

Magnesium oxide, calcium oxide and sodium oxide, because they are not part of, but serve to improve the sinterability of the alloy during pressing and grinding the grain of the alloy of its crystal lattice, they participate only in the process of its manufacture, in other words, they burn at high temperature and separate in the form of slag. Deoxidizing catalysts are needed to improve the sintering process of components already present in the composition. The final product does not contain the above oxides.

Claims (3)

1. Mixed cutting ceramic containing aluminum oxide and silicon oxide, characterized in that it additionally contains titanium carbide, tantalum carbide and tungsten carbide in the following ratio, wt.%: aluminum oxide Al ₂ O ₃ 27-30 silicon oxide SiO ₂ 27-31 tantalum carbide TaC 9-10 titanium carbide TiC 23-24 tungsten carbide WC 9-10 2. A method for manufacturing a cutting insert from mixed cutting ceramics according to claim 1, characterized in that a mixture of silicon oxide and aluminum oxide is calcined at a temperature of 1750-1760 ° C, subjected to fine vibrogrinding on a vibratory unit for 3.5-4.5 hours and dried, after drying, titanium carbide, tantalum carbide and tungsten carbide are added to the main composition and mixing is carried out until they are evenly distributed over the volume and the formation of an aqueous suspension, deoxidizing additives of catalysts in the form of magnesium oxide MgO, calcium oxide CaO, sodium oxide Na are introduced into the resulting aqueous suspension₂O and subjected to spray drying to obtain a mixture, after which the resulting mixture is pressed to form a cutting plate, subjected to sintering at a temperature of 3870-3950°C and short-term annealing with a holding time of 10.0-15.0 minutes at a temperature of 1650-1680°C, and the sintered plates are subjected to machining to obtain a roughness of the faces equal to 0.06-0.08 μm.