CN103820695B - Based on the Al of liquid sintering process 2o 3/ TiC coated carbides preparation method - Google Patents

Abstract

The invention discloses a kind of Al based on liquid sintering process ₂o ₃the preparation method of/TiC coated carbides, is characterized in that first adopting Liquid preparation methods to go out Al (OH) ₃/ Ti (OH) ₄core/shell structure colloidal sol, is then spin-coated on and reaches the Wimet billet surface of 85% ~ 95% through solid state sintering density and form Al ₂o ₃/ TiO ₂layer, carbothermic reduction reaction occurs for the CO atmosphere in recycling liquid sintering process and top layer makes TiO ₂be converted into TiC, finally produce Al ₂o ₃/ TiC coated carbides.Present invention process process is simple, is easy to control, and avoids Al ₂o ₃the problem of two kinds of coating staged gas phase deposition in/TiC coated carbides manufacturing processed, and coating process and matrix prepare the problem of proceed step by step, prepare Al based on liquid sintering process one step ₂o ₃/ TiC coated carbides.

Description

Based on the Al of liquid sintering process 2o 3/ TiC coated carbides preparation method

Technical field

The present invention relates to a kind of preparation method of coated carbides, particularly Al ₂o ₃the preparation method of/TiC coated carbides, belongs to powder metallurgy and Hardmetal materials field.

Background technology

Wimet is with infusibility transition metal carbides such as WC, TiC for base, and the iron family metals such as Co are binding agent, adopts the multiphase solid material that powder metallurgy process is prepared into.Since nineteen twenty-three Germany's invention WC-6%Co invention, through the development of nearly 90 years, Wimet has replaced rapid steel became current topmost cutter material, was described as " tooth of industry ".The appearance of the coating technology particularly occurred the seventies in last century, after making coating, cutter life improves 2 ~ 5 times.Hard alloy substrate applies one or more layers metal or nonmetallic compound film constitutes coated cutting tool, its obdurability is ensured by matrix, and high rigidity and wear resistance are solved by coating.Coating decreases the crescent hollow abrasion of Wimet in working angles as chemical barrier and thermodynamic barrier, along with production is to the requirement of high-level efficiency, high precision and high reliability, Cutting-Tool Coating Technology is paid much attention to, and current coated cutting tool accounts for inserted tool more than 70%.At present, coated material that inserted tool is applied (and combination) has tens kinds, topmostly comprises TiC, TiN, TiCN, Al ₂o ₃, TiAlN etc.Wherein Al ₂o ₃coating at high temperature has good thermostability, chemical stability, high rigidity and physical strength, anti-oxidant wearing and tearing and anti-diffusive wear performance, and TiC _xn _1-x(x=0 ~ 1) coating not only self performance is excellent but also be well typically used as the bottom of coating, Al with matrix bonding properties ₂o ₃/ TiC _xn _1-xthe collocation of (x=0 ~ 1) coating obtains application widely in high speed cutting field.

Traditional chemical vapour deposition (CVD) method and physical vapor deposition (PVD) method are at Al ₂o ₃/ TiC _xn _1-xachieve successfully in (x=0 ~ 1) coating manufacture, S.Canovic etc. have prepared the Al separated with 20nmTiC or TiN by CVD ₂o ₃coating, and the TiN/ κ – Al that the TiN layer of two-layer different thickness (50 and 600nm) separates ₂o ₃coating.A.Riedl etc. adopt LPCVD method at the first depositing Ti CN of WC-4TiC-8TaC/NbC-11Co carbide surface, then depositing Al ₂o ₃, coat-thickness is respectively 8 and 10 μm, and gaseous fraction is respectively TiCl ₄– CH ₃cN – H ₂– N ₂and AlCl ₃– CO – CO ₂– H ₂– H ₂s, depositing temperature is respectively 900 and 1000 DEG C, and gaseous tension is respectively 80 and 100mbar.X.M.Chen etc. prepare CVDTiN/TiCN/ κ-Al at WC-5.5 (Ti, Ta, Nb) C-6Co carbide surface ₂o ₃(α-Al ₂o ₃) coating, the depositing temperature of each layer is 950-1050 DEG C, 800-900 DEG C and 950-1050 DEG C respectively; Depositing time is respectively 0.5 – 1h, 1 – 4h and 2 – 6h; Gaseous tension is respectively 10 ~ 50kPa, 5 ~ 20kPa and 5 ~ 20kPa.

But, Al ₂o ₃and TiC _xn _1-xthe physical and mechanical property of layer is widely different, and when adopting traditional vapour deposition process, their depositing temperature, gaseous fraction, pressure are all not identical, can not disposable acquisition under the same conditions.Therefore, coating procedure needs proceed step by step, and the control of above-mentioned coating process parameter is very difficult.And these methods are all first sinter out hard alloy substrate, and then carry out coating process, therefore carbide matrix is known from experience through twice heating process of cooling, and therefore the preparation process of coated carbides also becomes complicated.While vapour deposition process is optimized in continuation, develop new coated carbides preparation method and have great importance undoubtedly.

Summary of the invention

The present invention is directed to current Al ₂o ₃two kinds of coating staged gas phase deposition in/TiC coated carbides manufacturing processed, hard alloy substrate preparation and coating process proceed step by step, complex technical process and unmanageable problem, propose first to adopt Liquid preparation methods to go out Al (OH) ₃/ Ti (OH) ₄core/shell structure colloidal sol, after being then spin-coated on solid state sintering, density is the Wimet billet surface formation Al of 85% ~ 95% ₂o ₃/ TiO ₂layer, carbothermic reduction reaction occurs for the CO atmosphere in recycling liquid sintering process and top layer makes TiO ₂be converted into TiC, finally produce Al ₂o ₃/ TiC coated carbides.

Al based on liquid sintering process of the present invention ₂o ₃the preparation method of/TiC coated carbides, is characterized in that comprising following steps successively:

(1) Al (OH) ₃/ Ti (OH) ₄prepared by core/shell structure colloidal sol: by Al (NO ₃) ₃be made into deionized water the solution that concentration expressed in percentage by volume is 0.5% ~ 3%, add ammoniacal liquor regulator solution pH value to 8 ~ 9, at 20 ~ 60 DEG C, stir 1 ~ 6h with magnetic stirring apparatus, then place 6 ~ 12h, form Al (OH) ₃colloidal sol; Add TiCl again ₄, make its concentration expressed in percentage by volume be Al (NO ₃) ₃5% ~ 45% of concentration expressed in percentage by volume, and add ammoniacal liquor adjust ph to 8 ~ 9, at 40 ~ 90 DEG C, stir 1 ~ 6h with magnetic stirring apparatus, then place 6 ~ 12h, generate Ti(OH) ₄coated Al (OH) ₃al (OH) ₃/ Ti(OH) ₄core/shell structure colloidal sol;

(2) hard alloy green body solid state sintering: take various raw material powder batching, TiC accounts for 0 ~ 15%, TaC and accounts for 0 ~ 15%, NbC and account for 0 ~ 10%, Co and account for 4 ~ 12% by weight percentage, and all the other are WC; Mixed powder through ball milling, filtration, drying, mix forming agent, compression moulding obtains hard alloy green body; Hard alloy green body is warmed up to 1150 ~ 1300 DEG C in vacuum sintering furnace, and vacuum tightness is 3 ~ 10Pa, and is incubated 1 ~ 3h to complete solid state sintering, and forming density is the base substrate of 85% ~ 95%;

(3) spin coating and Wimet billet surface Al ₂o ₃/ TiO ₂core/shell structure generates: by Al (OH) ₃/ Ti (OH) ₄core/shell structure colloidal sol is spin-coated on the Wimet billet surface after solid state sintering, during spin coating, every layer turns 15s under the rotating speed of 550r/min, 25s is turned again with the rotating speed of 1100r/min, every layer be painted with after at 115 ~ 230 DEG C, cure 1h and one deck under being coated with again after being cooled to 20 ~ 30 DEG C, the spin coating number of plies is 3 ~ 6 layers, forms Al in Wimet billet surface ₂o ₃/ TiO ₂core/shell structure;

(4) liquid phase sintering manufactures Al ₂o ₃/ TiC coated carbides: there is Al on surface ₂o ₃/ TiO ₂the Wimet base substrate of core/shell structure sinters under CO atmosphere in low pressure atmosphere sintering oven, and gaseous tension is 1 ~ 3MPa, and temperature is 1400 DEG C ~ 1500 DEG C, and soaking time is the Al of 0.5h, Wimet billet surface ₂o ₃/ TiO ₂there is carbothermic reduction reaction and be transformed into Al ₂o ₃/ TiC coating; Be filled with argon gas after insulation terminates and get rid of CO gas, maintenance argon pressure is 3 ~ 5MPa, and sintering temperature is constant, then is incubated 1 ~ 3h, realizes hard alloy substrate liquid phase sintering densification, prepares surface and have Al ₂o ₃the coated carbides of/TiC compound coating.

Al based on liquid sintering process of the present invention ₂o ₃the preparation method of/TiC coated carbides, it is further characterized in that:

(1) Al (NO ₃) ₃, TiCl ₄analytical pure is with ammoniacal liquor; Preparation Al (OH) ₃/ Ti (OH) ₄during core/shell structure colloidal sol, the speed of magnetic agitation is 20 ~ 50r/min;

(2) when prepared by hard alloy green body, Ball-milling Time is 24 ~ 72h, filters employing 400 eye mesh screen, adopts 85 ~ 100 DEG C of dryings, mix sodium butadiene rubber forming agent, make type at 300 ~ 500MPa pressure in the ratio of 70 ~ 90ml/kg;

(3), during hard alloy green body solid state sintering, heat-up rate is 5 ~ 15 DEG C/min;

(4) liquid phase sintering terminate after cooling rate be 5 ~ 15 DEG C/min.

The invention has the advantages that: (1) utilizes heterogeneous forming core principle in liquid phase, makes Ti(OH) ₄coated Al (OH) ₃colloid surface, forms Al (OH) ₃/ Ti(OH) ₄core/shell structure colloidal sol, recycling sintering carburizing atmosphere is converted into Al ₂o ₃/ TiC compound coating, technique is simple, is easy to control, need not gradation vapour deposition.(2) after hard alloy substrate solid state sintering, density and intensity improve, then carry out collosol coating and there will not be surface hydrolysis to be oxidized and defect; And basic contraction completely, can not cause the breakage of top coat after its solid state sintering because of dimensional contraction excessive during liquid phase sintering after spin coating.(3) Al ₂o ₃/ TiC compound coating is core/shell structure, is conducive to improving the bonding strength between coating.(4) be that carbon source realizes surface TiO with CO in liquid sintering process ₂to the conversion of TiC, avoid the destruction to carbon balance in hard alloy substrate.(5) based on liquid sintering process, two kinds of coatings are without the need to substep preparation, and coating and substrate manufacturing process also combine.

Accompanying drawing explanation

Fig. 1 the inventive method and conventional gas-phase sedimentation prepare Al ₂o ₃/ TiC coated carbides process schematic representation

embodiment.

Example 1: first by Al (NO ₃) ₃be made into deionized water the solution that concentration expressed in percentage by volume is 0.8%, add ammoniacal liquor regulator solution pH value to 8, stir 2h with magnetic stirring apparatus at 25 DEG C, the speed of magnetic agitation is 25r/mi, then places 8h, forms Al (OH) ₃colloidal sol; Add TiCl again ₄, making its concentration expressed in percentage by volume for being 0.16%, being equivalent to Al (NO ₃) ₃20% of concentration expressed in percentage by volume, and add ammoniacal liquor adjust ph to 8.2, at 50 DEG C, stir 1h with magnetic stirring apparatus, the speed of magnetic agitation is 25r/min, then places 10h, generates Ti(OH) ₄coated Al (OH) ₃al (OH) ₃/ Ti(OH) ₄core/shell structure colloidal sol, Al (NO ₃) ₃, TiCl ₄analytical pure is with ammoniacal liquor.Take various raw material powder batching again, TiC accounts for 3%, TaC and accounts for 2%, NbC and account for 2%, Co and account for 10% by weight percentage, and all the other are WC; Mixed powder filters through 56h ball milling, 400 eye mesh screens, 90 DEG C of dryings, to mix sodium butadiene rubber forming agent mix forming agent, make type obtain hard alloy green body at 350MPa pressure in the ratio of 70ml/kg; Hard alloy green body is warmed up to 1290 DEG C in vacuum sintering furnace, and heat-up rate is 6 DEG C/min, and vacuum tightness is 3Pa, and is incubated 1h to complete solid state sintering, and forming density is the base substrate of 88%.By Al (OH) ₃/ Ti (OH) ₄core/shell structure colloidal sol is spin-coated on the Wimet billet surface after solid state sintering, during spin coating, every layer turns 15s under the rotating speed of 550r/min, 25s is turned again with the rotating speed of 1100r/min, every layer be painted with after at 150 DEG C, cure 1h after and after being cooled to 25 DEG C be again coated with under one deck, the spin coating number of plies is 6 layers, forms Al in Wimet billet surface ₂o ₃/ TiO ₂core/shell structure.Finally, surface there is Al ₂o ₃/ TiO ₂the Wimet base substrate of core/shell structure sinters under CO atmosphere in low pressure atmosphere sintering oven, and gaseous tension is 1MPa, and temperature is 1440 DEG C, and soaking time is the Al of 0.5h, Wimet billet surface ₂o ₃/ TiO ₂there is carbothermic reduction reaction and be transformed into Al ₂o ₃/ TiC coating; Be filled with argon gas after insulation terminates and get rid of CO gas, maintenance argon pressure is 4MPa, and sintering temperature is constant, then is incubated 1h, realizes hard alloy substrate liquid phase sintering densification, and the cooling rate after liquid phase sintering terminates is 10 DEG C/min, finally prepares surface and has Al ₂o ₃the coated carbides of/TiC compound coating.

Example 2: first by Al (NO ₃) ₃be made into deionized water the solution that concentration expressed in percentage by volume is 3%, add ammoniacal liquor regulator solution pH value to 9, stir 5h with magnetic stirring apparatus at 50 DEG C, the speed of magnetic agitation is 50r/mi, then places 10h, forms Al (OH) ₃colloidal sol; Add TiCl again ₄, making its concentration expressed in percentage by volume for being 1.2%, being equivalent to Al (NO ₃) ₃40% of concentration expressed in percentage by volume, and add ammoniacal liquor adjust ph to 8.4, at 70 DEG C, stir 4h with magnetic stirring apparatus, the speed of magnetic agitation is 40r/min, then places 11h, generates Ti(OH) ₄coated Al (OH) ₃al (OH) ₃/ Ti(OH) ₄core/shell structure colloidal sol, Al (NO ₃) ₃, TiCl ₄analytical pure is with ammoniacal liquor.Take various raw material powder batching again, TaC accounts for 3%, Co and accounts for 8% by weight percentage, and all the other are WC; Mixed powder filters 95 DEG C of dryings through 48h ball milling, 400 eye mesh screens, mix sodium butadiene rubber forming agent in the ratio of 80ml/kg mixes forming agent, makes type obtain hard alloy green body at 300MPa pressure; Hard alloy green body is warmed up to 1250 DEG C in vacuum sintering furnace, and heat-up rate is 12 DEG C/min, and vacuum tightness is 6Pa, and is incubated 2h to complete solid state sintering, and forming density is the base substrate of 91%.By Al (OH) ₃/ Ti (OH) ₄core/shell structure colloidal sol is spin-coated on the Wimet billet surface after solid state sintering, during spin coating, every layer turns 15s under the rotating speed of 550r/min, 25s is turned again with the rotating speed of 1100r/min, every layer be painted with after at 200 DEG C, cure 1h after and after being cooled to 27 DEG C be again coated with under one deck, the spin coating number of plies is 4 layers, forms Al in Wimet billet surface ₂o ₃/ TiO ₂core/shell structure.Finally, surface there is Al ₂o ₃/ TiO ₂the Wimet base substrate of core/shell structure sinters under CO atmosphere in low pressure atmosphere sintering oven, and gaseous tension is 3MPa, and temperature is 1420 DEG C, and soaking time is the Al of 0.5h, Wimet billet surface ₂o ₃/ TiO ₂there is carbothermic reduction reaction and be transformed into Al ₂o ₃/ TiC coating; Be filled with argon gas after insulation terminates and get rid of CO gas, maintenance argon pressure is 5MPa, and sintering temperature is constant, then is incubated 1h, realizes hard alloy substrate liquid phase sintering densification, and the cooling rate after liquid phase sintering terminates is 5 DEG C/min, finally prepares surface and has Al ₂o ₃the coated carbides of/TiC compound coating.

Claims (1)

1. the Al based on liquid sintering process ₂o ₃the preparation method of/TiC coated carbides, is characterized in that comprising following steps successively:

(1) Al (OH) ₃/ Ti (OH) ₄prepared by core/shell structure colloidal sol: by Al (NO ₃) ₃be made into deionized water the solution that concentration expressed in percentage by volume is 0.5% ~ 3%, add ammoniacal liquor regulator solution pH value to 8 ~ 9, at 20 ~ 60 DEG C, stir 1 ~ 6h with magnetic stirring apparatus, then place 6 ~ 12h, form Al (OH) ₃colloidal sol; Add TiCl again ₄, make its concentration expressed in percentage by volume be Al (NO ₃) ₃5% ~ 45% of concentration expressed in percentage by volume, and add ammoniacal liquor adjust ph to 8 ~ 9, at 40 ~ 90 DEG C, stir 1 ~ 6h with magnetic stirring apparatus, then place 6 ~ 12h, generate Ti(OH) ₄coated Al (OH) ₃al (OH) ₃/ Ti(OH) ₄core/shell structure colloidal sol; Al (NO used ₃) ₃, TiCl ₄analytical pure is with ammoniacal liquor; Preparation Al (OH) ₃/ Ti (OH) ₄during core/shell structure colloidal sol, the speed of magnetic agitation is 20 ~ 50r/min;

(2) hard alloy green body solid state sintering: take various raw material powder batching, TiC accounts for 0 ~ 15%, TaC and accounts for 0 ~ 15%, NbC and account for 0 ~ 10%, Co and account for 4 ~ 12% by weight percentage, and all the other are WC; Mixed powder through ball milling, filtration, drying, mix forming agent, compression moulding obtains hard alloy green body; Time prepared by hard alloy green body, Ball-milling Time is 24 ~ 72h, filters employing 400 eye mesh screen, adopts 85 ~ 100 DEG C of dryings, mix sodium butadiene rubber forming agent, make type at 300 ~ 500MPa pressure in the ratio of 70 ~ 90ml/kg; Hard alloy green body is warmed up to 1150 ~ 1300 DEG C in vacuum sintering furnace, and heat-up rate is 5 ~ 15 DEG C/min, and vacuum tightness is 3 ~ 10Pa, and is incubated 1 ~ 3h to complete solid state sintering, and forming density is the base substrate of 85% ~ 95%;

(3) spin coating and Wimet billet surface Al ₂o ₃/ TiO ₂core/shell structure generates: by Al (OH) ₃/ Ti (OH) ₄core/shell structure colloidal sol is spin-coated on the Wimet billet surface after solid state sintering, during spin coating, every layer turns 15s under the rotating speed of 550r/min, 25s is turned again with the rotating speed of 1100r/min, every layer be painted with after at 115 ~ 230 DEG C, cure 1h and one deck under being coated with again after being cooled to 20 ~ 30 DEG C, the spin coating number of plies is 3 ~ 6 layers, forms Al in Wimet billet surface ₂o ₃/ TiO ₂core/shell structure;

(4) liquid phase sintering manufactures Al ₂o ₃/ TiC coated carbides: there is Al on surface ₂o ₃/ TiO ₂the Wimet base substrate of core/shell structure sinters under CO atmosphere in low pressure atmosphere sintering oven, and gaseous tension is 1 ~ 3MPa, and temperature is 1400 DEG C ~ 1500 DEG C, and soaking time is the Al of 0.5h, Wimet billet surface ₂o ₃/ TiO ₂there is carbothermic reduction reaction and be transformed into Al ₂o ₃/ TiC coating; Be filled with argon gas after insulation terminates and get rid of CO gas, maintenance argon pressure is 3 ~ 5MPa, and sintering temperature is constant, then is incubated 1 ~ 3h, realizes hard alloy substrate liquid phase sintering densification, and the cooling rate after liquid phase sintering terminates is 5 ~ 15 DEG C/min; Finally prepare surface and there is Al ₂o ₃the coated carbides of/TiC compound coating.