CN1590572A - Sintering technology of nano-grade tungsten cobalt mixed powder - Google Patents
Sintering technology of nano-grade tungsten cobalt mixed powder Download PDFInfo
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- CN1590572A CN1590572A CN 03150683 CN03150683A CN1590572A CN 1590572 A CN1590572 A CN 1590572A CN 03150683 CN03150683 CN 03150683 CN 03150683 A CN03150683 A CN 03150683A CN 1590572 A CN1590572 A CN 1590572A
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Abstract
A sinter process for nano-class W-Co mixture powder includes preparing nano-class W-Co mixture powder, adding additive, stirring, adding paraffin wax, vacuum drying, granulating, cold isostatic pressing, trimming, vacuum sintering at 1000 deg.C, sintering at 1150-1200 deg.c while filling high-pressure inertial gas, natural cooling and sand-blasting. It has high hardness and strength.
Description
Technical field
The present invention relates to the sintering art of metal-powder, especially relate to a kind of sintering process of nano level tungsten cobalt mixed powder.
Background technology
Metal-powder is of many uses, has very big market potential, and the method for producing submicron metal is a lot.The sintering process of hard alloy metal powder is one of them very the key link.The sintering of traditional Wimet micron order mixed powder is the liquid phase sintering that the high temperature more than 1340 ℃ (tungsten carbide wc, cobalt Co two component eutectic temperature) carries out, the tungsten carbide wc grain fineness number of conventional top hammer will be grown up in the liquid phase sintering process to 1200-2000nm, crystal grain is excessive, often reduce its performance, can not satisfy the industrial production needs of high requirement.Because specific surface, interfacial effect and the small-size effect of nanocrystal, nanometer tungsten cobalt WC-Co mixed powder is in sintering process, and the motivating force of tungsten carbide wc grain growth is very big, is dozens or even hundreds of times of common tungsten carbide wc powder.There are some researches show, use traditional lqiuid phase sintering method, in the 10-15 that reaches the liquid phase sintering temperature minute, the nanometer tungsten carbide WC grain has just taken place fully to grow up.
As seen, in order to obtain superfine crystal particle top hammer, the very key of growing up of control nanometer tungsten cobalt WC-Co mixed powder tungsten carbide wc crystal grain in sintering process.Tradition micron order tungsten cobalt mixed powder, it suppresses constituent element is that form with carbide adds, with the tungsten carbide wc powder through mechanical ball milling, fragmentation, disperse remix.Because it is very little to suppress the addition of constituent element, its mixed effect is not good, distribution in powder is also inhomogeneous, in the sintering process of liquid phase, the growing up of regional tungsten carbide wc crystal grain that inhibitor is many suppressed and refinement, and growing up of the regional tungsten carbide wc crystal grain that inhibitor is few is more abundant, thereby cause that the tungsten carbide wc grain growth is inhomogeneous, cause the microstructure of Wimet unequal, even the tungsten carbide wc coarse grain occurs, finally influence the physical and mechanical properties and the use properties of alloy.
Sintering behavior with dilatometry research tungsten cobalt dust is found, the contraction of nanoscale powder is different from micron powder, the sintering of Nanometre grade tungsten carbide WC particle can carry out under solid-state, and the densification of micron-sized tungsten carbide wc particulate can only be finished by liquid phase sintering, and the powder grain degree is more little, and the temperature that obtains complete densification in solid phase and liquid phase sintering is just low more.
Summary of the invention
The present invention mainly is that to solve the existing crystal grain that makes alloy of existing SINTERING TECHNOLOGY excessive, and the sintered article gap is bigger, and very fine and close, alloy strength is owed high technical problem.
The present invention has also solved in the existing in prior technology metal-powder and to have suppressed constituent element and add very unrationally, and defective appears in alloy structure easily behind the sintering, and difficulty can satisfy the technical problem of the industrial production needs of high requirement etc.
Above-mentioned technical problem of the present invention is mainly solved by following technical proposals: be made of following consecutive steps:
A. produce nano level tungsten cobalt WC-Co mixed powder with fluidisation thermochemistry conversion method, and add additive, mix; B. mix the wax moulding agent, after the vacuum-drying, make particle; C. adopt isostatic cool pressing to be pressed into blank, and crude green body is repaired; D. sintering blank in vacuum sintering furnace, the low-temperature sintering below 1000 ℃; E. sintering blank in vacuum sintering furnace, the high temperature solid-phase sintering in the time of 1150-1200 ℃, and charge into the high-pressure inert gas of 6-10MPa; F. sintering blank in vacuum sintering furnace, sintering temperature is 1250 ℃ a high temperature solid-phase sintering; G. after taking out, naturally cooling, qualified product are made in sandblast.Because product is in closing on the high temperature solid-state of liquid phase and charge under the working condition of high-pressure inert gas of 6-10MPa and carry out sintering, changed composition and fusion mode that traditional grain growth is faced upward the system constituent element, make intercrystalline space diminish, structure is more fine and close.
As preferably, described tungsten cobalt WC-Co mixed powder is tungsten carbide wc, the pre-alloyed powder that suppresses constituent element and cobalt Co, and the grain fineness number of powder is 20-80nm.The superfine grain fineness number helps reducing sintering temperature, makes tungsten cobalt mixed powder adopt high temperature solid-phase sintering to get final product complete densification, simplifies sintering process.
As preferably, tungsten carbide wc content is 91.20-92.18% in the described tungsten cobalt WC-Co mixed powder, cobalt Co content is 6.8-7.8%, and suppressing constituent element is rare metal soluble salt and ammonium metawolframate, the cobaltous carbonate liquid phase is compound and form through the charing of fluidized-bed gas phase, and its content is 0.01-2.00%.Like this, the distribution that suppresses constituent element and tungsten carbide wc, cobalt Co is quite even, and granularity is very little, suppresses the effect highly significant of tungsten carbide wc grain growth.
As preferably, in the low-temperature sintering stage in the sintering oven below 1000 ℃, temperature rise rate is 0.04 ℃/s, and the temperature rise time was controlled at 6.7 hours-7.0 hours usually.Temperature rise so slowly helps the discharge of wax moulding agent, prevents that paraffin volatilization is too fast and the blank cracking that causes suppressing.
As preferably, the high temperature solid-phase sintering that reaches 1150-1200 ℃ in the sintering oven is incubated 1 hour after the stage, and charges into the high-pressure inert gas of 6-10MPa in advance.Rare gas element can change radiative transfer in the sintering oven into transmission of heat by convection, make compacting top hammer blank internal and external temperature more even, can also make the densification in top hammer high temperature solid-phase sintering stage strengthen, this is extremely important to obtaining the uniform superfine crystal particle of inside and outside weave construction top hammer.
Therefore, it is short that the present invention has technical process, and easy to operate, utility appliance is few, save facility investment, reduce cost of manufacture, sintering gained ultrafine gain size top hammer excellent product performance, its tungsten carbide wc grain fineness number is less than 300nm, hardness HRA93.5, intensity 3700Mpa, the disposable qualification rate of product reaches 95% with first-class characteristics, also can be in order to produce other the Industrial products of having relatively high expectations.This technology has reached advanced international standard.
Description of drawings
Accompanying drawing 1 is the metallograph (* 3000 times) that the tungsten cobalt WC-Co composite powder of common process production sinters Wimet into;
Accompanying drawing 2 is metallographs (* 3000 times) that nanometer tungsten cobalt WC-Co composite powder that the present invention produces sinters Wimet into.
Embodiment
Below by embodiment, and in conjunction with the accompanying drawings, technical scheme of the present invention is described in further detail.
Embodiment: with sintering ultrafine gain size top hammer is example, utilization of the present invention be the nano level tungsten cobalt WC-Co mixed powder that fluidisation thermochemistry conversion method is produced, this powder is WC, the pre-alloyed powder that suppresses constituent element and Co, the grain fineness number of powder is 20-80nm, wherein WC content is 92.2%, Co content is 7.8%, suppressing constituent element is rare metal soluble salt and ammonium metawolframate, the cobaltous carbonate liquid phase is compound and form through the charing of fluidized-bed gas phase, its content is very little, the distribution that suppresses constituent element and WC, Co is quite even, and granularity is very little.
According to the design needs, get a certain amount of above-mentioned mixed powder, and add additive, mix, mix the wax moulding agent then, after the vacuum-drying, make particle, adopt isostatic cool pressing to be pressed into blank, and crude green body is repaired.Blank is placed on carries out sintering in the vacuum sintering furnace, in the low-temperature sintering stage below 1000 ℃, temperature rise rate is 0.04 ℃/s, the temperature rise time was controlled at about 6.9 hours, temperature rise so slowly helps the discharge of wax moulding agent, prevents that paraffin volatilization is too fast and the blank cracking that causes suppressing.The high temperature solid-phase sintering that reaches 1200 ℃ in the sintering oven is incubated 1 hour after the stage, and charges into the high-pressure inert gas of 8MPa in advance.Rare gas element can change radiative transfer in the sintering oven into transmission of heat by convection, make compacting top hammer blank internal and external temperature more even, can also make the densification in top hammer high temperature solid-phase sintering stage strengthen, this is extremely important to obtaining the uniform superfine crystal particle of inside and outside weave construction top hammer.Be warming up to 1250 ℃ then, the sintering certain hour, after the taking-up, naturally cooling, qualified product are made in sandblast.
Comparison diagram 1 and Fig. 2, the Wimet grain fineness number that sinters into of the present invention is more even as can be known, and densification degree is higher, because getting the grain fineness number of tungsten cobalt mixed powder is 20-80nm, adopt high temperature solid-phase sintering to get final product complete densification, and the distribution that suppresses constituent element and WC, Co is quite even, and granularity is very little, suppress the effect highly significant that WC grain is grown up, the tungsten carbide wc grain fineness number is less than 300nm in the product, hardness HRA93.5, intensity 3700Mpa, the disposable qualification rate of product reaches more than 95%, has simplified sintering process, has reduced production cost.
Claims (8)
1. the sintering process of a nano level tungsten cobalt mixed powder is made of following consecutive steps:
A. produce nano level tungsten cobalt WC-C with fluidisation thermochemistry conversion method
0Mixed powder, and add additive, mix;
B. mix the wax moulding agent, after the vacuum-drying, make particle;
C. adopt isostatic cool pressing to be pressed into blank, and crude green body is repaired;
D. first sintering blank in vacuum sintering furnace, the low-temperature sintering below 1000 ℃;
E. sintering blank in vacuum sintering furnace again, the high temperature solid-phase sintering in the time of 1150-1200 ℃, and charge into the high-pressure inert gas of 6-10MPa;
F. sintering blank in vacuum sintering furnace, sintering temperature is 1250 ℃ of high temperature solid-phase sinterings;
G. after taking out, naturally cooling, qualified product are made in sandblast.
2. the sintering process of nano level tungsten cobalt mixed powder according to claim 1 is characterized in that described tungsten cobalt WC-C
0Mixed powder is WC, inhibition constituent element and C
0Pre-alloyed powder, the grain fineness number of powder is 20-80nm.
3. the sintering process of nano level tungsten cobalt mixed powder according to claim 1 and 2 is characterized in that described tungsten cobalt WC-C
0WC content is 91.2%-92.18% in the mixed powder, C
0Content is 6.8%-7.8%, and suppressing constituent element is rare metal soluble salt and ammonium metawolframate, the cobaltous carbonate liquid phase is compound and form through the charing of fluidized-bed gas phase, and its content is 0.01%-2.0%.
4. the sintering process of nano level tungsten cobalt mixed powder according to claim 1 and 2 is characterized in that the low-temperature sintering stage below 1000 ℃ in the sintering oven, and temperature rise rate is 0.04 ℃/s, and the temperature rise time was controlled at 6.7 hours-7.0 hours usually.
5. the sintering process of nano level tungsten cobalt mixed powder according to claim 3 is characterized in that the low-temperature sintering stage below 1000 ℃ in the sintering oven, and temperature rise rate is 0.04 ℃/s, and the temperature rise time was controlled at 6.7 hours-7.0 hours usually.
6. the sintering process of nano level tungsten cobalt mixed powder according to claim 1 and 2, the high temperature solid-phase sintering that it is characterized in that reaching in the sintering oven 1150-1200 ℃ was incubated 1 hour, and charges into the high-pressure inert gas of 6-10MPa in advance after the stage.
7. the sintering process of nano level tungsten cobalt mixed powder according to claim 3, the high temperature solid-phase sintering that it is characterized in that reaching in the sintering oven 1150-1200 ℃ was incubated 1 hour, and charges into the high-pressure inert gas of 6-10MPa in advance after the stage.
8. the sintering process of nano level tungsten cobalt mixed powder according to claim 4, the high temperature solid-phase sintering that it is characterized in that reaching in the sintering oven 1150-1200 ℃ was incubated 1 hour, and charges into the high-pressure inert gas of 6-10MPa in advance after the stage.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100363131C (en) * | 2005-12-12 | 2008-01-23 | 北京科技大学 | Method for preparing grain-size-contrdlable superfine crystallite tungsten and tungsten-copper composite material |
| CN101754825B (en) * | 2007-07-18 | 2012-04-18 | 株式会社Ihi | Process for producing electrode for discharge surface treatment, and electrode for discharge surface treatment |
| CN103060760A (en) * | 2012-11-28 | 2013-04-24 | 厦门虹鹭钨钼工业有限公司 | Preparation method for molybdenum-titanium alloy target |
| CN105537599A (en) * | 2015-12-21 | 2016-05-04 | 龙岩学院 | Method for manufacturing WC-Co nano composite powder through mechanical alloying |
| CN108165861A (en) * | 2018-02-08 | 2018-06-15 | 合肥工业大学 | A kind of method that nanometer WC-6Co composite powders to add Co powder prepare ultra-fine cemented carbide as raw material |
| CN109295334A (en) * | 2018-09-30 | 2019-02-01 | 合肥工业大学 | A method of high-performance carbide is prepared using WC-6Co composite powder as raw material |
| CN111363941A (en) * | 2020-03-27 | 2020-07-03 | 陕西理工大学 | Polygonal microstructure tungsten alloy material and preparation method and application thereof |
-
2003
- 2003-08-25 CN CN 03150683 patent/CN1590572A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100363131C (en) * | 2005-12-12 | 2008-01-23 | 北京科技大学 | Method for preparing grain-size-contrdlable superfine crystallite tungsten and tungsten-copper composite material |
| CN101754825B (en) * | 2007-07-18 | 2012-04-18 | 株式会社Ihi | Process for producing electrode for discharge surface treatment, and electrode for discharge surface treatment |
| CN103060760A (en) * | 2012-11-28 | 2013-04-24 | 厦门虹鹭钨钼工业有限公司 | Preparation method for molybdenum-titanium alloy target |
| CN105537599A (en) * | 2015-12-21 | 2016-05-04 | 龙岩学院 | Method for manufacturing WC-Co nano composite powder through mechanical alloying |
| CN108165861A (en) * | 2018-02-08 | 2018-06-15 | 合肥工业大学 | A kind of method that nanometer WC-6Co composite powders to add Co powder prepare ultra-fine cemented carbide as raw material |
| CN109295334A (en) * | 2018-09-30 | 2019-02-01 | 合肥工业大学 | A method of high-performance carbide is prepared using WC-6Co composite powder as raw material |
| CN111363941A (en) * | 2020-03-27 | 2020-07-03 | 陕西理工大学 | Polygonal microstructure tungsten alloy material and preparation method and application thereof |
| CN111363941B (en) * | 2020-03-27 | 2021-06-29 | 陕西理工大学 | Polygonal microstructure tungsten alloy material and preparation method and application thereof |
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