CN100348482C

CN100348482C - Production method of needle-shaped tungsten carbide powder

Info

Publication number: CN100348482C
Application number: CNB200410040330XA
Authority: CN
Inventors: 何宪峰; 周永贵; 刘清才; 黄新; 石建华
Original assignee: Chongqing University; Zigong Cemented Carbide Co Ltd
Current assignee: Chongqing University; Zigong Cemented Carbide Co Ltd
Priority date: 2004-07-30
Filing date: 2004-07-30
Publication date: 2007-11-14
Anticipated expiration: 2024-07-30
Also published as: CN1597510A

Abstract

The present invention belongs to a production method of needle-shaped tungsten carbide powder for hard alloy production. The production method comprises the steps: raw material mixture, reducing treatment, carbon and cobalt mixture, primary carbonizing treatment, carbon and cobalt mixture for the second time, secondary carbonizing treatment and ball milling operation, and thus, crystal needle-shaped WC powder is obtained. In the production method, because WO3 is used as raw material, Ni and Na or K are used as catalysts for reducing treatment, and reduced W powder is carbonized through two steps under the condition of adding the catalysts, WC crystal grains grow in a needle shape. The production method has the advantages of advanced production process, high stability and reliability, high needle-shaped degree of WC powder metallographic structure, wide adaptation range of producing hard alloy and obvious effect on fiber reinforcement of alloy. Compared with hard alloy products prepared from the conventional WC powder under the corresponding condition, the hard alloy product prepared by the production method has the characteristics of high strength and hardness, high toughness and abrasion resistance, excellent integrative mechanical property, etc. The production method overcomes the defects of WC crystal grains which are equiaxial triangular prisms or polygon prisms through a one-step carbonization method, and alloy product defects caused by the WC crystal grains.

Description

The production method of needle-shaped tungsten carbide powder

Technical field

The invention belongs to the production method of a kind of CEMENTED CARBIDE PRODUCTION with raw material powder, particularly a kind of crystal grain is the production method of acicular wolfram varbide (WC) powder.The WC powder that adopts this method to produce can be widely used in produces cutting tool, wear resistant tools and mine probing, exploitation with instrument etc.

Background technology

WC-Co base binary alloy not only has good anti-breaking tenacity, and has high rigidity, thereby is widely used as instruments such as cutting, wear-resisting and mine probing, exploitation.In the production of this type of alloy, determined the overall performance of alloy largely as the inner quality of the WC powder of main raw material.Conventional WC powder is used for producing WC-Co base binary alloy, its metallographic structure WC grain and axle triangular prism or multiedge cylinder such as is generally.Its production method is to adopt blue tungsten (WO _2.9) be main raw material, after handling, reduction forms through disposable carbonizing treatment again.Characteristics such as batching is simple though this method has, technical process is short; But owing to adopt a step carbonization, its carbonization speed is too fast, and the WC of generation more easily makes WC grain explosion in process of growth because of the density variation between itself and the W, thereby the WC grain pattern that generates under this condition can not form (growing into) needle-like or tabular.Thereby the Wimet that adopts this type of WC powder production in use WC grain is easily transferred to the wear resistance that has reduced alloy, and its hardness is relative with toughness relatively poor, has also shortened work-ing life.At this defective, the Masaki Kobayashi of Japan etc. disclose a kind of use " Co-W-C mixture ten carbon " powder mix in " development of pan enhanced Wimet " (" external refractory metal and mechanically resistant material " in December, 2000, the 16th volume 12 phase P41-45) or " W+ graphite+Co " powder mix is made raw material, in sintering process, form plate-like WC by chemical reaction, have higher hardness, toughness, intensity and cutting ability though this Wimet with WC of plate-like crystal morphology is compared with conventional Wimet.But it is to adopt the raw material powder mix of fixing (uniqueness) that this type of WC crystalline phase is organized as discous Wimet, in sintering process, form, thereby there is an one. the composition of alloy (composition) scope and product category are subjected to great restriction, as not adding compositions such as TiC, NC, otherwise the preferential growth that will stop WC grain crystal face in sintering process causes its crystal grain can not plate-likeization; Its two, poor stability forms owing to the plate-like WC grain makes its crystal face grow up unusually according to qualifications in sintering process, it is bigger that the ratio that the plate-like WC grain generates is influenced by sintering process and proportioning raw materials, defectives such as constant product quality difference.

Summary of the invention

The objective of the invention is the production method that a kind of WC grain pattern of research and development is acicular needle-shaped tungsten carbide powder on the basis of conventional WC powder production method, the length-to-diameter ratio of the crystal grain of the WC powder of being produced is generally more than 4: 1; To reach production technique advanced person, reliable, WC powder Functionality, quality and appealing design, stable performance, be convenient to suitability for industrialized production, and adopt that this powder production Wimet has that production technique is simple, reliable, applied range, constant product quality and have arch bridge and make fiber reinforcement effect such as crackle kinking, hardness, toughness, intensity height, purpose such as wear resistance is good.

Solution of the present invention is to adopt WO ₃(yellow tungsten) is for raw material and add the catalyst reduction processing, step (level) carbonization with background technology simultaneously changes two step (level) carbonization techniques into, the mixed carbon comtent of the carbonization first time is reduced to the 60-78% of theoretical carbon amount, avoid crystal grain explosion in process of growth to reduce carburizing reagent speed; Carbonizing treatment makes residual tungsten nuclear and W more for the second time ₂C is transformed into WC and impels its grain growing to become needle-like; Thereby realize its purpose.Therefore, method of the present invention comprises:

A, batching: with WO ₃Raw material powder and catalyzer are sent in the mixing tank and are mixed; Catalyzer and add-on thereof are with WO ₃Weight is counted the Ni of 30-300ppm and Na or the K of 150-650ppm;

B, reduction are handled: pack into the mixed powder that is made in the graphite boat and send in the reduction furnace, at H ₂Reduction was handled 5-8 hour under protection and the 980-1270 ℃ of temperature, and the 40-100 mesh sieve is crossed in gained W powder cooling back, to remove impurity;

C, join carbon and catalyst cobalt: above-mentioned gained W powder is sent in the ball mill together with C powder (being roughly equal to the 60-78% that whole W generate the required theoretical carbon amount of WC) and the Co powder of 150-650ppm of its weight 3.7-4.7%, is mixed, the W+C+Co mixed powder;

D, carbonizing treatment: above-mentioned mixed powder packed into send in the carbon tube furnace behind the graphite boat, under 1750-2150 ℃ of temperature carbonizing treatment 8-10 hour, cooling back ball milling became the powder of 40-100 mesh sieve, must contain W nuclear, W ₂The tungsten carbide powder of C.

E, secondary are joined carbon and cobalt: will send in the ball mill through the powder of above-mentioned carbonizing treatment, and supply the C amount by the 93.0-101.1% of the theoretical carbon content of total WC, and add the Co powder of 150-350ppm, ball milling mixes;

F, secondary carbonization and ball-milling processing: will prepare pack into graphite boat and sending in the carbon tube furnace of gained mixed powder by E, under 1650-2050 ℃ of temperature carbonizing treatment 5-10 hour; Gained WC piece is crossed the 40-200 sieve behind ball milling, promptly getting crystal morphology is acicular WC powder.

In order to help mixing, in the batching before reduction is handled, catalyst n i that is added and Na or K all add with the aqueous solution of its soluble salt, and the solution amount that is added is by the heavy WO of every kg ₃Powder adds preparation of mixed aqueous solution amount and the adding of Ni and Na or the K of 100-150ml, and is fashionable when adding with the aqueous solution, again with the compound oven dry, stand-by after mixing.And the soluble salt of described Ni and Na or K, wherein the soluble salt of Ni is Ni (NO ₃) ₂, the soluble salt of Na, K is respectively NaCl, KCl.And described reduction furnace is the molybdenum filament electric reduction furnace.

The present invention is owing to change conventional one step of WC powder process for carbonization production two step carbonizations into and add different catalyzer in reduction processing and carbonizing treatment process, both avoided causing crystal grain explosion fragmentation, promoted effectively again that WC grain grew into needle-like because of carbonization speed is too fast.The WC powder that adopts production method of the present invention to produce is used to produce hart metal product, regardless of its prescription, all can not change WC intrinsic crystalline-granular texture in sintering process, its product has fiber reinforcement effects such as the crackle of making kinking, arch bridge effect, and in use WC grain also is difficult for being transferred to.Thereby, the present invention has production technique advanced person, reliable and stable, WC flour gold phase structure spiculation degree height, the fiber reinforcement effect that is used to produce Wimet wide accommodation, product is obvious, the hart metal product of being produced with conventional WC powder has intensity, hardness height more again under corresponding situation, characteristics such as toughness and wear resistance are good, and comprehensive mechanical performance is better.

Accompanying drawing and description of drawings

Fig. 1 is embodiment 1, WC powder (500 times) metallograph;

Fig. 2 is embodiment 2, WC powder (500 times) metallograph;

White is WC grain among the figure, and black part is divided into the copper base.

Embodiment 1

A, batching: with 10kgFSSS (Fisher particle size) 18.8 μ m, concentration class is 18.43 WO ₃Raw material powder places the double cone mixing tank, with 1.56gNi (NO ₃) ₂And 6.36gNaCl be dissolved in altogether be made into the aqueous solution in the 1.5L water after, under agitation condition, spray in the mixing tank, send into drying in oven to bulky powder after mixing, stand-by.

B, reduction are handled: above-mentioned powder is packed into send in the molybdenum filament electric reduction furnace, at H in the graphite boat ₂Reduction was handled 6.5 hours under protection and the 1100 ℃ of temperature, and 80 mesh sieves are crossed to remove impurity in the cooling back.

C, join carbon and catalyst cobalt: the W powder 7kg of back gained is handled in the reduction of learning from else's experience, and adds in the ball mill together with the carbon black powders and the 1.75gCo powder of 267.3 grams, and ball milling mixes, the W+C+Co mixed powder.

D, carbonizing treatment: above-mentioned mixed powder is sent in the carbon tube furnace, and carbonizing treatment is 9 hours under 1950 ℃ of temperature; Ball milling became the powder of 80 mesh sieves behind the furnace cooling, must contain W nuclear, W ₂The tungsten carbide powder of C.

E, secondary are joined carbon and cobalt: the powder 7kg of the above-mentioned carbonizing treatment of learning from else's experience sends in the ball mill and adds 182g carbon black powder and 2.19Co powder, and ball milling mixes.

F, secondary carbonization and ball-milling processing: above-mentioned preparation gained mixed powder is reinstalled graphite boat and send in the carbon tube furnace, carbonizing treatment is 8 hours under 1800 ℃ of temperature; Treat the cooling of WC piece after ball milling is crossed 100 mesh sieves, promptly getting crystal morphology is acicular WC powder product.Accompanying drawing 1, be 500 times of metallographs of present embodiment product.

Implement 2

Present embodiment batching and reduction are handled and adopted FSSS (Fisher particle size) is 20.2 μ m, and concentration class is 46.47 WO ₃10kg is a raw material, adds catalyst n i (NO ₃) ₂6.22g and the mixed aqueous solution 1.5L of NaCl 12.72g, mix and be dried into loose mixed powder after, send in the reduction furnace at H in the boat of packing into ₂Reduction was handled 7 hours under protection and the 1150 ℃ of temperature, after the removal of impurities of sieving the W powder.

Join carbon, add catalyst cobalt and carbonizing treatment: get above-mentioned tungsten powder 7kg, carbon black powder 322g, Co powder 3.15g goes in the ball mill altogether, ball milling mixes back dress boat, and carbonizing treatment is 9 hours under 2000 ℃ of temperature, and cooling back ball milling sieves, and must contain W nuclear and W ₂The tungsten carbide powder of C.

Secondary is joined carbon, cobalt and carbonizing treatment: get above-mentioned powder 7kg through the carbonizing treatment gained first time, carbon black powder 159kg, Co powder 2.5g, ball milling mixes back dress boat, goes in the carbon tube furnace, and carbonizing treatment is 7.5 hours under 1850 ℃ of temperature, gets the WC piece.

All the other technologies are all same with embodiment 1.Fig. 2 is 500 times of metallographs of present embodiment gained WC powder product.

Claims

1, a kind of production method of needle-shaped tungsten carbide powder, this method comprises:

A, batching: with WO ₃Raw material powder and catalyzer are sent in the mixing tank, mix; Catalyzer and add-on thereof are with WO ₃Weight is counted the Ni of 30-300ppm and Na or the K of 150-650ppm;

C, join carbon and catalyst cobalt: above-mentioned gained W powder is sent in the ball mill together with the C powder of its weight 3.7-4.7% and the Co powder of 150-650ppm, is mixed, the W+C+Co mixed powder;

D, carbonizing treatment: above-mentioned mixed powder is packed into behind the graphite boat, send in the carbon tube furnace, under 1750-2150 ℃ of temperature carbonizing treatment 8-10 hour, cooling back ball milling became the powder of 40-100 mesh sieve, must contain W nuclear, W ₂The tungsten carbide powder of C;

E, secondary are joined carbon and cobalt: will send in the ball mill through the powder of above-mentioned carbonizing treatment, and supply C and add the Co powder of 150-350ppm by the 93.0-101.1% of the theoretical carbon content of total WC, ball milling mixes;

F, secondary carbonization and ball-milling processing: will prepare pack into graphite boat and sending in the carbon tube furnace of gained mixed powder by E, under 1650-2050 ℃ of temperature carbonizing treatment 5-10 hour; Gained WC piece is crossed the 40-200 mesh sieve behind ball milling, promptly getting crystal morphology is acicular WC powder.

2, by the described production method of claim 1, the catalyst n i of adding and Na or K all add with the aqueous solution of its soluble salt, and the solution amount that is added is by the heavy WO of every kg ₃Powder adds preparation of mixed aqueous solution amount and the adding of Ni and Na or the K of 100-150ml; Fashionable when adding with the above-mentioned aqueous solution,, stand-by after mixing again with the mixed powder oven dry.

3, by the described production method of claim 2, the soluble salt of described Ni and Na or K, wherein the soluble salt of Ni is Ni (NO ₃) ₂, the soluble salt of Na, K then is respectively NaCl, KCl.

4, by the described production method of claim 1, its reduction furnace is the molybdenum filament electric reduction furnace.