CN102465242A

CN102465242A - A whisker toughened cermet material

Info

Publication number: CN102465242A
Application number: CN2010105388424A
Authority: CN
Inventors: 黎晓桃; 罗兵辉; 郑洪�
Original assignee: Chinalco Shanghai Copper Co ltd; Central South University
Current assignee: China Copper Shanghai Copper Co Ltd; Central South University
Priority date: 2010-11-10
Filing date: 2010-11-10
Publication date: 2012-05-23
Anticipated expiration: 2030-11-10
Also published as: CN102465242B

Abstract

The invention relates to the technical field of whisker toughened metal ceramic materials. The whisker toughened cermet material consists of a cermet matrix material and nickel-plated silicon carbide whiskers, and specifically comprises 30-60 w% of tungsten, 20-40 w% of chromium, 6-20 w% of aluminum oxide, 0.5-7 w% of lanthanum oxide, 2-18 w% of nickel and 0.1-15 w% of nickel-plated silicon carbide whiskers. The whisker toughened cermet material has the hardness of 86-92 HRA, the bending strength of more than or equal to 650MPa and the fracture toughness of more than or equal to 13 MPa-m^1/2The thermal shock resistance stability is more than or equal to 300MPa at 1000 ℃. When the copper alloy extrusion die is applied to a hot extrusion die, compared with the existing hot extrusion die, the cracking resistance is obviously improved, the average service life is prolonged to more than 106 copper alloy sleeves from 55 copper alloy sleeves when a certain copper alloy is extruded, and the average service life is greatly prolonged.

Description

A kind of Whisker-toughened cermet material

Technical field

The present invention relates to a kind of Whisker-toughened cermet material technology field.

Background technology

Temperature 650-1100 ℃ of copper alloy hot extrusion blank, hot-extrusion mold is on active service under mal-conditions such as high temperature, high pressure, wearing and tearing and thermal fatigue, and it is that heat fatigue cracking causes and breaks that hot-extrusion mold lost efficacy main.Patent CN1093121A, CN86107658A, CN1506483A etc. pass through metal W, Cr, Ni, Fe, Co and ceramic phase Al ₂O ₃, La ₂O ₃, (Ti, W, Ta, Nb) adjustment of C composition and granularity and complete processing control, the cermet material that makes has better comprehensive performance, utilize its hot-extrusion mold that makes when certain copper alloy tube of extruding mean life 55 times/cover.But still having deficiency, mean life is still undesirable.Trace it to its cause, though strong hardness and wear resistance are high, toughness is not enough, and heat-shock resistance or poor heat stability produce the inefficacy of breaking when being prone to cause the mold hot extruding.

The heat-shock resistance of material is the general performance of its mechanical property and thermal property.Thermal shock fatigue relates to crackle nucleation and crack propagation, promptly in the thermal shock environment from crackle nucleation, expansion, to the whole process of final fracture.Research draws, and the power of crack propagation is elastic strain energy, and crack propagation process is that elastic strain energy progressively discharges and pays the process that crack surfaces can increment, in case strain energy can transform totally to crack surfaces, the expansion of crackle has just stopped.Therefore controlling the crackle nucleation, expanding is to improve toughness and heat-shock resistance key.Big quantity research shows, through in ceramic phase, adding the second phase particle, fiber or whisker, not only can improve obdurability, can also significantly improve heat-shock resistance.Mainly be that the introducing of second phase produces various highly malleablized mechanism and causes crack deflection, crackle pinning etc. effectively to stop the formation and the expansion of thermal shock crackle.As passing through at Al ₂O ₃Add partially stabilized ZrO in the ceramic matrix ₂, can improve Al ₂O ₃The heat-shock resistance of ceramic composite.As w (ZrO ₂)=20% can make the thermal shock temperature reach 310 ℃.Al ₂O ₃The thermal shock resistance of-SiCW matrix material obviously is superior to Al ₂O ₃-TiC matrix material.Reason is the whisker bridging and the energy of extracting, the comprehensive action of toughening mechanisms such as crack deflection has dissipated the thermal shock crack propagation greatly of crystal whisker toughened pottery; Increased the resistance of crack propagation; Therefore; The existence of whisker is to playing extremely strong inhibition by the caused crack propagation of thermal shock, stoped the expansion and the merging of crackle effectively by the various toughening mechanisms that whisker produced, and makes matrix material show the ability of very superior anti-thermal shock.In addition, W, Cu, Mo, metallicss such as Ni can obviously improve Al ₂O ₃Obdurability, reduce Young's modulus, increase thermal conductivity, thereby improve the thermal shock resistance of material.As the Al that adopts hot pressed sintering to prepare ₂O ₃/ Ni 20% netty compound material, pressing in method is in 300-900 ℃ of quenching temperature scope, and heat-shock resistance is apparently higher than one-component ceramic.

Summary of the invention

The object of the invention just provides a kind of good thermostability that not only has, and high red hardness and excellent abrasive also possess H.T., the Whisker-toughened cermet material that improve high temperature life.

For reaching above-mentioned purpose, the technical scheme that the present invention takes is following:

A kind of Whisker-toughened cermet material; Be made up of sintering metal matrix material and nickel plating silicon carbide whisker, concrete component is the tungsten of 30-60w%, the chromium of 20-40w%, the aluminium sesquioxide of 6-20w%, the lanthanum sesquioxide of 0.5-7w%, the nickel of 2-18w% and the nickel plating silicon carbide whisker of 0.1%-15w%.

Tungsten and chromium in the above-mentioned sintering metal matrix material, tungsten has good heat resistance and red hardness, and chromium has high wear resistance and high temperature oxidation resistance; Aluminium sesquioxide and lanthanum sesquioxide can form sosoloid, improve the heat-shock resistance and the hot strength of material; Nickel has improved the bonding strength of metal with pottery, improves the processing characteristics of cermet material; The silicon carbide whisker that adopts nickel plating is as toughening material, and purpose is to improve the wettability of silicon carbide whisker and sintering metal matrix, to improve the intensity and the fracture toughness property of cermet mold.

Whisker-toughened cermet material of the present invention is compared with existing material and is increased to 124/cover by 55/cover mean life as copper alloy extrusion die, and be enhanced about more than once work-ing life.

Whisker-toughened cermet preparation methods according to the invention may further comprise the steps:

(1) silicon carbide whisker nickel plating is carried out chemical nickel plating after process purifying, sensitization, the activation treatment respectively again with silicon carbide whisker;

(2) raw materials mix, first each component raw material with sintering metal matrix material places according to required weight percent carries out wet-milling in the ball mill; The nickel plating silicon carbide whisker that makes according to required weight percent adding step (1) then mixes;

(3) hot-forming, with step (2) mixed raw materials hot pressed sintering in protective gas.

In the above-mentioned step (2), the preferred yg8 ball of ball grinder that uses during each component raw material wet-milling of sintering metal matrix material; The preferred planetary ball mill of ball mill that adopts; Preferred 15～28 hours of ball milling time, rotating speed 200～250rpm; Preferred 2～8 hours of the time of mixing and ball milling behind the adding nickel plating silicon carbide whisker, rotating speed 150～250rpm.

The condition of preferred technology is during above-mentioned step (3) hot pressed sintering: 20～55 ℃/min of temperature rise rate; Progressively slowly be pressurized to 10～25MPa when being heated to 1150-1250 ℃; Insulation, pressurize when sintering temperature reaches 1350～1600 ℃; The heat-insulation pressure keeping time is 25-35min, cools to room temperature afterwards with the furnace, and rate of temperature fall is at 25-35 ℃/min.The sintering protective atmosphere is preferably high pure nitrogen.

Beneficial effect of the present invention: Whisker-toughened cermet material provided by the invention, through detecting its hardness 86～92HRA, bending strength (20 ℃)>=650MPa, fracture toughness property>=13MPam ^1/2, 1000 ℃ of following thermal shock residual strength>=300MPa of anti-thermal shock stability.Whisker-toughened cermet material of the present invention is applied to hot-extrusion mold; Comparing the cracking resistance ability with existing hot-extrusion mold obviously improves; Extruding during certain copper alloy mean life by 55/cover be increased to 106/more than the cover, significantly improve mean life.

Embodiment

Embodiment 1-5

1.SiC the nickel plating of whisker

Adopting SiC whisker mean diameter is 10～100nm, and length is 200～1000nm, and fusing point is 2700 ℃, and density is 3.2g/cm ², Young's modulus is 414GPa, thermal expansivity is 3.27 * 10 ^-6K ^-1Carry out chemical nickel plating by following mode:

(1) purifying: the SiC whisker that with tonburden is 2g/L is by 1: 1: 1 HNO ₃-HCl-H ₂Stirring and UW disperse 20～30min in the O mixed solution, and heated and boiled 50min cleans with water purification, at last with the SiC whisker that obtains purifying after the abundant washing and filtering of deionized water.

(2) sensitization: in 1: 4: 5 ratio SiC whisker and SnCl with purification process ₂-HCl-H ₂The O mixed solution stirs together, and UW carries out the dispersion of 20～30min, with the SiC whisker that obtains sensitization after the abundant washing and filtering of deionized water.

(3) activation: SiC whisker that sensitization is handled and PbCl in 1: 1: 2 ratio ₂-HCl mixed solution stirs together, and UW carries out the dispersion of 20～30min, with obtaining activatory SiC whisker after the abundant washing and filtering of deionized water.

(4) chemical nickel plating: the SiC whisker that will pass through activation treatment joins nickel-plating liquid (NiSO ₄.6H ₂O, NaC ₂H ₃O ₂, NaH ₂PO ₂.H ₂O, Na ₃C ₆H ₅O ₇.2H ₂O, X 2073, ratio is 10: 10: 10: 5: 1) in; Realize SiC whisker plating nickel on surface through electroless plating; Control nickel-plating liquid pH value is 5～6 during nickel plating, and the nickel plating temperature is 30～50 ℃, and the reaction times is 10～20min; Disperse through stirring and UW, again through cleaning, drying.

2. raw materials mix

Ratio shown in the according to the form below 1 places ball grinder to adopt the yg8 ball on planetary ball mill, to carry out wet-milling, 20 hours time, rotating speed 200rpm in tungsten, chromium, aluminium sesquioxide, lanthanum sesquioxide, nickel earlier; Add the nickel plating silicon carbide whisker again, mix, 5 hours time, rotating speed 200rpm.

Table 1 Whisker-toughened cermet composition (wt.%)

Embodiment	W	Cr	Al ₂O ₃	Ni	La ₂O ₃	Nickel plating SiC whisker
							1	35	40	11	10	1	3
2	35	37	11	10	1	6
							3	35	33	11	10	1	10
4	47	23	7	15	5	3
							5	53.7	22	18	5	0.8	0.5

3. hot-forming

Behind described constituent materials ball milling, in the graphite jig of packing into, carry out hot pressed sintering.The hot-pressing sintering technique process is: 20～25 ℃/min of temperature rise rate; Progressively slowly be pressurized to 25MPa when being heated to 1200 ℃, insulation, pressurize when sintering temperature reaches 1400 ℃, the heat-insulation pressure keeping time is 30min; Cool to room temperature afterwards with the furnace, the about 30 ℃/min of rate of temperature fall.The sintering protective atmosphere is a high pure nitrogen.

The performance of mould that obtains five kinds of Whisker-toughened cermet materials and preparation thereof is as shown in table 2 below.

The performance of table 2 Whisker-toughened cermet material and mould thereof

Annotate: heat-shock resistance adopts chilling-intensity method, is about to sample and is heated to 1000 ℃, and insulation 20min is quenched in the water medium retained strength of test.

Claims

1. A whisker-toughened cermet material, consisting of a cermet base material and nickel-plated silicon carbide whiskers, the specific components being 30-60w% tungsten, 20-40w% chromium, 6-20w% tertiary Aluminum oxide, 0.5-7w% lanthanum trioxide, 2-18w% nickel and 0.1%-15w% nickel-plated silicon carbide whiskers.

2. the preparation method of whisker toughened cermet material described in claim 1, comprises the following steps:

(1) Silicon carbide whiskers are nickel-plated, and the silicon carbide whiskers are purified, sensitized, and activated before electroless nickel plating;

(2) Mixing of raw materials, first place the raw materials of each component of the cermet matrix material in a ball mill for wet grinding according to the required weight percentage; then add the nickel-plated silicon carbide whiskers prepared in step (1) according to the required weight percentage to mix;

(3) hot press forming, the raw materials mixed in step (2) are hot pressed and sintered in a protective gas.

3. The preparation method of whisker-toughened cermet material as claimed in claim 2, characterized in that: the ball mill used in the above step (2) is a planetary ball mill, and the ball mill jar used is yg8 balls.

4. the preparation method of whisker toughened cermet material as claimed in claim 2, it is characterized in that: above-mentioned step (2) ball milling time is 15～28 hours, rotating speed 200～250rpm; Add nickel-plated silicon carbide whisker The post-mixing ball milling time is 2 to 8 hours, and the rotation speed is 150 to 250 rpm.

5. The preparation method of whisker-toughened cermet material as claimed in claim 2, characterized in that: the conditions of the above-mentioned step (3) hot pressing sintering are: heating rate 20～55°C/min, heating to 1150°C When the temperature is -1250℃, the pressure is gradually increased to 10~25MPa. When the sintering temperature reaches 1350~1600℃, heat preservation and pressure preservation are carried out. The time of heat preservation and pressure preservation is 25-35min. min.

6. The preparation method of whisker-toughened cermet material as claimed in claim 2, characterized in that: the sintering protective atmosphere in the above-mentioned step (3) is pure nitrogen.