CN104388723A - Granulometric and gradient hard alloy prepared by using liquid-phase infiltration method and preparation method thereof - Google Patents

Granulometric and gradient hard alloy prepared by using liquid-phase infiltration method and preparation method thereof Download PDF

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CN104388723A
CN104388723A CN201410669898.1A CN201410669898A CN104388723A CN 104388723 A CN104388723 A CN 104388723A CN 201410669898 A CN201410669898 A CN 201410669898A CN 104388723 A CN104388723 A CN 104388723A
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gradient
core
grain
grain inhibitor
preparation
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CN104388723B (en
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刘超
李文强
聂洪波
吴冲浒
冯炎建
曾祺森
肖满斗
文晓
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Xiamen Tungsten Co Ltd
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Abstract

The invention discloses a granulometric and gradient hard alloy prepared by using a liquid-phase infiltration method and a preparation method thereof; and, by optimizing the attachment manner of a grain inhibitor on the surface of a green body and changing the disperse manner of the grain inhibitor, high-temperature disperse sintering and time are optimized, so that the granulometric and gradient alloy with the gradient layer of being more than or equal to 0.2 mm and the maximal thickness of being more than 6 mm can be prepared. The method disclosed by the invention is simple in process, low in equipment investment, easy to control the process and low in production cost; the thickness of the granulometric and gradient layer of the WC-Co granulometric and gradient hard alloy prepared by using the method is more than or equal to 0.2 mm; the maximal thickness of the WC-Co granulometric and gradient hard alloy is more than 6 mm; the average size of WC grains in the core is about 1.05-1.5 times of that of WC grains in the surface layer; the Hv1 hardness of the surface layer is about 1.03-1.2 times of that of the core; furthermore, the alloy does not have Co gradient change; because of having smaller WC grains, the surface layer has higher hardness and abrasive resistance; because of having larger WC grains, the core has better toughness; in addition, because of having enough machining allowance, the alloy can be applied in various products more easily.

Description

Granular gradient Wimet that a kind of liquid infiltration legal system is standby and preparation method thereof
Technical field
The present invention relates to Hardmetal materials manufacturing technology field, particularly relate to standby granular gradient Wimet of a kind of liquid infiltration legal system and preparation method thereof.
Background technology
General WC-Co hard alloy is the equally distributed homogeneous material of a kind of WC and Co, because it has high rigidity, and high strength, high-wearing feature, high deformation resistance, the good characteristics such as high corrosion resistance, are widely used in industry and the fields such as mould, machining and probing excavation.
In various material, hardness and toughness are shifting relation mostly, and WC-Co hard alloy is like this too, and we are difficult to the WC-Co hard alloy that acquisition has high rigidity and high tenacity simultaneously.But, in modern industry, particularly cutting, mining and die industry in, we wish acquisition hardness, toughness, the product that wear resistance has both simultaneously.The appearance of graded alloy is considered to solve the very important means of of above-mentioned requirements, and by the weave construction of adjustment top layer and core, we can obtain different functional layers, thus make it be applied to different service conditions.
Granular gradient WC-Co hard alloy refers to from sample in whole or in part, and top layer is to core, and WC mean grain size presents the Wimet becoming graded that is large or that reduce.The preparation method of existing granular gradient WC-Co hard alloy mainly contains two kinds, the first is layering compacting, the WC-Co mixed powder different by WC mean grain size obtains the green compact with different grain size layer by multiple tracks suppression process, such as, patent publication No. JP2014-105354, disclosed by US5541006, CA101545058, CN102453822 etc.Although the method for this layering compacting can obtain granular gradient alloy, it has following problem: (1) pressing process is very complicated, is only applicable to the green compact of simple shape; (2) granular gradient exists only on pressure direction; (3) WC powder that multiple mean particle size is different is needed; (4) shrinkage coefficient due to different grain size layer is different, easily produces stress concentration in interface, in sintering and compacting, easily cause cracking, also easy fracture in using.
Second method is the method for surface attachment grain inhibitor, such as, disclosed by patent publication No. US5623723, JP1992-128330, CN102209599, CN103752833 etc.But for this method, the granularity layers variable thickness mentioned by current various countries patent documentation mostly is about 0.2mm, be also just say, the product that this method is produced does not possess process redundancy substantially.And, all there is Co gradient (top layer Co content is higher or lower than 2% ~ 4% of core Co content) in the WC-Co granular gradient alloy prepared by current this method, when granular gradient district (surface region) Co content is higher than normal matrix, can surface hardness be reduced, reduce the effect that change of granularity is brought; When Co content in granular gradient district is lower than normal matrix, can surface brittleness be increased, in use easily produce the problems such as cracking, fracture.、
Except above-mentioned two kinds of methods, patent publication No. JP2006-188749 also discloses a kind of M 3c, M 12c lacks the method for carbon compound prepared sizes graded alloy, the top layer Co content extremely low (≤2wt.%) of this method, and need through pre-burning, and the operations such as carburizing treatment, significantly add the preparation process of material.
Summary of the invention
The object of the invention is to the deficiency overcoming prior art, granular gradient Wimet providing a kind of liquid infiltration legal system standby and preparation method thereof, this alloy has sufficient process redundancy, thickness can reach more than 6mm, there is not Co gradient, surperficial wc grain size is less, has higher hardness and wear resistance, core wc grain size is comparatively large, has good toughness; Macroscopically showing as, surface hardness is high, and wear resistance is good, overall tough and tensile, can be used for cutting, the industry such as digging and mould; Further, because this granular gradient alloy has thicker gradient layer, there is sufficient process redundancy, can easierly be applied in various product.
The technical solution adopted for the present invention to solve the technical problems is: the granular gradient Wimet that a kind of liquid infiltration legal system is standby, comprises WC and Co, and wherein, Co content accounts for the 3.wt% ~ 20.wt% of WC and Co total amount; Also comprise containing Cr, V, Ta, Nb, Ti, Zr, one or more grain inhibitor elements in Hf, Mo, and the concentration of contained element is progressively reduce from described alloy surface to core, its surface concentration is not higher than the 1wt.% of WC, Co and contained element total amount, and its core concentration is minimum can be 0wt.%; The WC mean grain size of described alloy is in increasing gradually from top layer to core, and the mean grain size of its core is 1.05 ~ 1.5 times of surface.
The hardness of described alloy shows as in reducing gradually from surface to core, and its surface hardness is 1.03 ~ 1.2 times of core, and the hardness of alloy shows as there is not Co gradient from surface to core.
Described top layer is the region that the grain inhibitor of span sample is coated with that the distance of wiping one's face is no more than 100 μm; Described core refers to that the ratio of contained constituent content and Co content is the region of contained element/Co<0.75%, or is coated with the distance of the wiping one's face region more than 6mm apart from grain inhibitor.
The surface of described alloy is granular gradient layer to the region between core, and the contained constituent content in this region and the ratio of Co content are element/Co<10% contained by 0.75%<.
A preparation method for the granular gradient Wimet that liquid infiltration legal system is standby, comprises the steps:
A. raw material is chosen:
WC powder: be the WC powder of single mean particle size;
Co powder: be the Co powder of single mean particle size;
Forming agent: be paraffin, polyoxyethylene glycol.
Grain inhibitor: containing carbide or the oxide compound of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo;
B. compound preparation: the required mixed powder of 3.wt% ~ 20.wt% preparation accounting for WC and Co total amount according to Co content, WC-Co compound is prepared after wet-milling, drying process, wherein, the forming agent of the 1 ~ 2wt.% accounting for WC, Co and forming agent total amount is mixed before wet-milling or after wet-milling;
C. green compact preparation: the green compact according to the requirement preset, compound being pressed into required shape;
D. grain inhibitor mixed solution preparation: will containing the carbide of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo or the powder of oxide compound and water, alcohol, in polyoxyethylene glycol, one or more solvent prepare grain inhibitor mixed solution.Wherein containing the carbide of one or more grain inhibitor elements or the proportional range of oxide compound and solution in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo is 0.1 ~ 1.5g/ml;
E. adhere to: the region needing to realize granular gradient grain inhibitor mixed solution prepared in step D being applied to the green compact prepared by step C;
F. sinter: the green compact being coated with grain inhibitor are carried out high temperature sintering process, thus obtain granular gradient Wimet.
Described high temperature sintering process sinters under vacuum, wherein, the heat-up rate between 900 ~ 1280 DEG C is not higher than 2 DEG C/min, and sintering temperature controls at 1320 ~ 1550 DEG C, soaking time controls at 0.5 ~ 4h, and sintering oven internal pressure remains on 60 ~ 2000Pa.
Described high temperature sintering process sinters under overpressure condition, heat-up rate wherein between 900 ~ 1280 DEG C is not higher than 2 DEG C/min, sintering temperature controls at 1320 ~ 1550 DEG C, and soaking time controls at 0.5 ~ 4h, and in sintering oven, Ar gas dividing potential drop remains on 0.5 ~ 9.5MPa.
Adopt the WC-Co granular gradient Wimet prepared by above-mentioned technique, granular gradient layer thickness can reach more than 6mm, the mean grain size of core WC grain is about 1.05 ~ 1.5 times of the size of the mean grain size of top layer WC grain, top layer HV1 hardness is about 1.03 ~ 1.2 times of core Hv1 hardness, and this alloy does not exist the graded of Co.
Granular gradient Wimet that a kind of liquid infiltration legal system of the present invention is standby and preparation method thereof, it is the adhering mode by improving grain inhibitor, traditional High temperature diffusion is changed to the mode that low temperature liquid phase infiltration (room temperature ~ 600 DEG C) and High temperature diffusion (600 DEG C ~ sintering temperature) combines, the temperature and time of one-step optimization High temperature diffusion of going forward side by side; Thus prepared the thickest granular gradient alloy reaching more than 6mm of gradient layer.
The present invention adopts alcohol, water, the solvent that one or more solvents in polyoxyethylene glycol and paraffin or polyoxyethylene glycol can dissolve each other to a certain extent is deployed into mixed solvent, and will containing Cr, V, Ta, Nb, Ti, Zr, in Hf, Mo, the carbide of one or more grain inhibitor elements or oxide compound add and are deployed into grain inhibitor mixing solutions.During room temperature, after this grain inhibitor mixing solutions is attached to green surface, alcohol in solution, water, polyoxyethylene glycol etc. can and the paraffin in green compact or polyoxyethylene glycol produce dissolving each other to a certain extent, thus drive grain inhibitor internally to move from surface, in addition, in the temperature-rise period of sintering, in cold stage (room temperature ~ 600 DEG C), grain inhibitor can produce similar migration equally, thus significantly increase the penetration distance (low temperature liquid phase infiltration) of grain inhibitor.At hot stage, the carrying out between 900 ~ 1280 DEG C is slowly heated up, and grain inhibitor is spread further and homogenizing, thus obtains equally distributed granular gradient Wimet.
In general, containing the carbide of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo or oxide compound as in green surface enrichment, can be lower because of blank surface carbon potential in sintering process, thus produce the phenomenon of rich surface Co.The present invention adopts moisture, alcohol, and one or more solvents in polyoxyethylene glycol, as the one of additive, make its Sync enrichment in grain inhibitor enrichment of element district, thus effects on surface carbon potential have done making up to a certain extent, thus avoided the generation of Co gradient.
Compared with prior art, the invention has the beneficial effects as follows:
The adhering mode of grain inhibitor is changed to liquid attachment by the present invention, makes it can be applied to more shape.Traditional High temperature diffusion is changed to the mode that low temperature osmotic and High temperature diffusion combine by the present invention, the temperature and time of one-step optimization High temperature diffusion of going forward side by side.About low temperature osmotic, because containing water in the mixed solution of grain inhibitor, alcohol, the materials such as polyoxyethylene glycol, can and green compact in paraffin produce dissolving to a certain extent, thus make grain inhibitor element from attachment surface to internal diffusion in room temperature or the lower temperature region in sintering.About temperature and the optimization of High temperature diffusion, between its best spreading area, heat-up rate is slowed down for different grain inhibitor elements, increase its diffusion time, promote the internally low concentration region diffusion from high surface levels region further of grain inhibitor element, and make it even at short range wireless internal diffusion.The present invention uses moisture, alcohol, and one or more solvents in polyoxyethylene glycol, as the one of the composition of mixing attachment liquid, avoid the generation of Co gradient.
The present invention, by optimizing grain inhibitor in green surface adhering mode, changes its diffusion way, optimizes sintering and the time of High temperature diffusion, thus has prepared gradient layer >=0.2mm, the thickest granular gradient alloy reaching more than 6mm.The method technique is simple, facility investment is few, process is easy to control, production cost is low, its WC-Co granular gradient Wimet prepared, granular gradient layer thickness >=0.2mm, the thickest more than the 6mm that reaches, the mean size of core WC grain is about 1.05 ~ 1.5 times of the mean size of top layer WC grain, and top layer Hv1 hardness is about 1.03 ~ 1.2 times of core Hv1 hardness, and this alloy does not exist the graded of Co, surface wc grain size is less, have higher hardness and wear resistance, core wc grain size is comparatively large, has good toughness; Macroscopically showing as, surface hardness is high, and wear resistance is good, overall tough and tensile, can be used for cutting, the industry such as digging and mould; Further, because this granular gradient alloy has thicker gradient layer, there is sufficient process redundancy, can easierly be applied in various product.
Below in conjunction with drawings and Examples, the present invention is described in further detail; But granular gradient Wimet that a kind of liquid infiltration legal system of the present invention is standby and preparation method thereof is not limited to embodiment.
Accompanying drawing explanation
Fig. 1 is the Cr of embodiment one granular gradient alloy of the present invention 2c 3the microstructure of attachment surface;
Fig. 2 is the distance Cr of embodiment one granular gradient alloy of the present invention 2c 3the microstructure at attachment surface 6mm place;
Fig. 3 is that embodiment one granular gradient alloy of the present invention is from Cr 2c 3attachment surface is to distance Cr 2c 3attachment surface 6mm place's changes in hardness and Cr/Co value;
Fig. 4 is that the Co content of embodiment one granular gradient alloy of the present invention is from Cr 2c 3attachment surface is to distance Cr 2c 3the change state at attachment surface 6mm place;
Fig. 5 is the Cr of embodiment two granular gradient alloy of the present invention 2c 3the microstructure of attachment surface;
Fig. 6 is the distance Cr of embodiment two granular gradient alloy of the present invention 2c 3the microstructure at attachment surface 6mm place;
Fig. 7 is that embodiment two granular gradient alloy of the present invention is from Cr 2c 3attachment surface is to distance Cr 2c 3attachment surface 6mm place's changes in hardness and Cr/Co value;
Fig. 8 is that the Co content of embodiment two granular gradient alloy of the present invention is from Cr 2c 3attachment surface is to distance Cr 2c 3the change state at attachment surface 6mm place;
Fig. 9 is the Cr of embodiment three granular gradient alloy of the present invention 2c 3the microstructure of attachment surface;
Figure 10 is the distance Cr of embodiment three granular gradient alloy of the present invention 2c 3the microstructure at attachment surface 6mm place;
Figure 11 is that embodiment three granular gradient alloy of the present invention is from Cr 2c 3attachment surface is to distance Cr 2c 3attachment surface 6mm place's changes in hardness and Cr/Co value;
Figure 12 is that the Co content of embodiment three granular gradient alloy of the present invention is from Cr 2c 3attachment surface is to distance Cr 2c 3the change state at attachment surface 6mm place.
Embodiment
Embodiment
The granular gradient Wimet that a kind of liquid infiltration legal system of the present invention is standby, comprise WC and Co, wherein, Co content accounts for the 3.wt% ~ 20.wt% of WC and Co total amount; Also comprise containing Cr, V, Ta, Nb, Ti, Zr, one or more grain inhibitor elements in Hf, Mo, and the concentration of contained element is progressively reduce from described alloy surface to core, its surface concentration is not higher than the 1wt.% of WC, Co and contained element total amount, and its core concentration is minimum can be 0wt.%; The WC mean grain size of described alloy is in increasing gradually from top layer to core, and the mean grain size of its core is 1.05 ~ 1.5 times of surface.
The hardness of described alloy shows as in reducing gradually from surface to core, and its surface hardness is 1.03 ~ 1.2 times of core, and the hardness of alloy shows as there is not Co gradient from surface to core.
Described top layer is the region that the grain inhibitor of span sample is coated with that the distance of wiping one's face is no more than 100 μm; Described core refers to that the ratio of contained constituent content and Co content is the region of contained element/Co<0.75%, or is coated with the distance of the wiping one's face region more than 6mm apart from grain inhibitor.
The surface of described alloy is granular gradient layer to the region between core, and the contained constituent content in this region and the ratio of Co content are element/Co<10% contained by 0.75%<.
The preparation method of the granular gradient Wimet that a kind of liquid infiltration legal system of the present invention is standby, comprises the steps:
A. raw material is chosen:
WC powder: be the WC powder of single mean particle size;
Co powder: be the Co powder of single mean particle size;
Forming agent: be paraffin, polyoxyethylene glycol.
Grain inhibitor: containing carbide or the oxide compound of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo;
B. compound preparation: the required mixed powder of 3.wt% ~ 20.wt% preparation accounting for WC and Co total amount according to Co content, WC-Co compound is prepared after wet-milling, drying process, wherein, the forming agent of the 1 ~ 2wt.% accounting for WC, Co and forming agent total amount is mixed before wet-milling or after wet-milling;
C. green compact preparation: the green compact according to the requirement preset, compound being pressed into required shape;
D. grain inhibitor mixed solution preparation: will containing the carbide of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo or the powder of oxide compound and water, alcohol, in polyoxyethylene glycol, one or more solvent prepare grain inhibitor mixed solution.Wherein containing the carbide of one or more grain inhibitor elements or the proportional range of oxide compound and solution in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo is 0.1 ~ 1.5g/ml;
E. adhere to: the region needing to realize granular gradient grain inhibitor mixed solution prepared in step D being applied to the green compact prepared by step C;
F. sinter: the green compact being coated with grain inhibitor are carried out high temperature sintering process, thus obtain granular gradient Wimet.
Described high temperature sintering process sinters under vacuum, wherein, the heat-up rate between 900 ~ 1280 DEG C is not higher than 2 DEG C/min, and sintering temperature controls at 1320 ~ 1550 DEG C, soaking time controls at 0.5 ~ 4h, and sintering oven internal pressure remains on 60 ~ 2000Pa.
Described high temperature sintering process sinters under overpressure condition, heat-up rate wherein between 900 ~ 1280 DEG C is not higher than 2 DEG C/min, sintering temperature controls at 1320 ~ 1550 DEG C, and soaking time controls at 0.5 ~ 4h, and in sintering oven, Ar gas dividing potential drop remains on 0.5 ~ 9.5MPa.
Adopt the WC-Co granular gradient Wimet prepared by above-mentioned technique, granular gradient layer thickness can reach more than 6mm, the mean grain size of core WC grain is about 1.05 ~ 1.5 times of the size of the mean grain size of top layer WC grain, top layer HV1 hardness is about 1.03 ~ 1.2 times of core Hv1 hardness, and this alloy does not exist the graded of Co.
The greatest problem adopting grain inhibitor prepared sizes graded alloy how to control grain inhibitor to produce uniform Gradient distribution in the product.A large amount of solid-phase grain inhibitor is adhered at green surface when method in the past used is all room temperatures, in high-temperature sintering process, make grain inhibitor produce from high density to lower concentration from main diffusion, but because the diffusion of grain inhibitor is comparatively slow, the granular gradient layer that this method is produced generally is only 0.2mm.As extended sintering time in a large number, then can cause the abnormal growth of crystal grain.The present invention is by improving the adhering mode of grain inhibitor, traditional High temperature diffusion is changed to the mode that low temperature liquid phase infiltration (room temperature ~ 600 DEG C) and High temperature diffusion (600 DEG C ~ sintering temperature) combines, the temperature and time of one-step optimization High temperature diffusion of going forward side by side.Thus prepared the thickest granular gradient alloy reaching more than 6mm of gradient layer.
WC-Co hard alloy is in the process of compacting green compact, and usually can add the organism such as polyoxyethylene glycol or paraffin as forming agent, these forming agents are evenly distributed in green compact with the form of the particulate be interconnected.When being warming up to about 400 DEG C, these organism can remove, thus in the green compact of presintering, form a large amount of connection micropores.The present invention adopts alcohol, water, the solvent that one or more solvents in polyoxyethylene glycol and paraffin or polyoxyethylene glycol can dissolve each other to a certain extent is deployed into mixed solvent, and will containing Cr, V, Ta, Nb, Ti, Zr, in Hf, Mo, the carbide of one or more grain inhibitor elements or oxide compound add and are deployed into grain inhibitor mixing solutions.During room temperature, after this grain inhibitor mixing solutions is attached to green surface, alcohol in solution, water, polyoxyethylene glycol etc. can and the paraffin in green compact or polyoxyethylene glycol produce dissolving each other to a certain extent, thus drive grain inhibitor internally to move from surface, in addition, in the temperature-rise period of sintering, in cold stage (room temperature ~ 600 DEG C), grain inhibitor can produce similar migration equally, thus significantly increase the penetration distance (low temperature liquid phase infiltration) of grain inhibitor.At hot stage, the carrying out between 900 ~ 1280 DEG C is slowly heated up, and grain inhibitor is spread further and homogenizing, thus obtains equally distributed granular gradient Wimet.
In general, containing the carbide of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo or oxide compound as in green surface enrichment, can be lower because of blank surface carbon potential in sintering process, thus produce the phenomenon of rich surface Co.The present invention adopts moisture, alcohol, and one or more solvents in polyoxyethylene glycol, as the one of additive, make its Sync enrichment in grain inhibitor enrichment of element district, thus effects on surface carbon potential have done making up to a certain extent, thus avoided the generation of Co gradient.
The present invention, by optimizing grain inhibitor in green surface adhering mode, changes its diffusion way, optimizes sintering and the time of High temperature diffusion, thus has prepared gradient layer >=0.2mm, the thickest granular gradient alloy reaching more than 6mm.The method technique is simple, facility investment is few, process is easy to control, production cost is low, its WC-Co granular gradient Wimet prepared, granular gradient layer thickness >=0.2mm, the thickest more than the 6mm that reaches, the mean size of core WC grain is about 1.05 ~ 1.5 times of the mean size of top layer WC grain, and top layer Hv1 hardness is about 1.03 ~ 1.2 times of core Hv1 hardness, and this alloy does not exist the graded of Co.
Below in conjunction with three object lessons, to further illustrate standby granular gradient Wimet of a kind of liquid infiltration legal system of the present invention and preparation method thereof.
Embodiment one
(1) mean particle size is selected to be the thin tungsten carbide powder of 0.8 μm that Xiamen Golden Egret Special Alloy Co., Ltd produces, the thin cobalt powder of 0.8 μm, according to the proportioning of WC-10.3wt.%Co, make medium with raw spirit and carry out wet-milling in roller ball mill, ratio of grinding media to material is 4:1, liquid-solid ratio is 250mL/kg, and ball milling 48h final vacuum is dry, obtains WC-10.3wt.%Co compound.
(2) dry after dried WC-10.3wt.%Co compound being mixed the paraffin of 2wt.%, then cross 80 eye mesh screens, granulate, make compound have certain mobility.
(3) the granulation compound obtained in step (2) is pressed into pressed compact, pressing pressure is 15MPa.
(4) by Cr 2c 3with alcohol, water, polyoxyethylene glycol is mixed with the grain inhibitor solution of 0.35g/ml.
(5) solution configured in step (4) is spread upon pressed compact surface prepared in step (3).
(6) sintered under vacuum by the pressed compact being coated with grain inhibitor in step (5), sintering temperature controls at 1420 DEG C, and soaking time is 2h, and the heat-up rate wherein between 950 ~ 1150 DEG C is 2 DEG C/min, then furnace cooling.
Quantitative assay for constituent content in sample uses EPMA (JXA-8530F, JEOL) point analysis (radius: 50 μm) in is to Co, the content of Cr is analyzed, measurement range is grain inhibitor attachment surface extremely distance grain inhibitor attachment surface 6mm place, is spaced apart 0.5mm.Hardness test adopts dimension formula hardness test, and test specification is the same.The measurement of the mean grain size of WC adopts the testing method specified in ISO4499, measures the crystal grain of more than 250.
The gradient layer of the WC-Co granular gradient alloy adopting above-mentioned technique to prepare can reach more than 6mm, its Cr 2c 3the microstructure of attachment surface is shown in accompanying drawing 1, and the mean grain size of its WC is about 0.59 μm, apart from Cr 2c 3the microstructure at attachment surface 6mm place is shown in accompanying drawing 2, and the mean grain size of its WC is about 0.74 μm.Apart from Cr 2c 3the WC mean grain size at attachment surface 6mm place is about Cr 2c 31.25 times of attachment surface.Cr 2c 3the dimension formula hardness of attachment surface is 1627Hv1, apart from Cr 2c 3the dimension formula hardness at attachment surface 6mm place is 1524Hv1, and the hardness of attachment surface is about 1.067 times of 6mm place.From Cr 2c 3attachment surface is to distance Cr 2c 3attachment surface 6mm place's changes in hardness and Cr/Co value are shown in accompanying drawing 3.Co content is from Cr 2c 3attachment surface is to distance Cr 2c 3accompanying drawing 4 is shown in the change at attachment surface 6mm place.
Embodiment two
(1) selecting mean particle size to be the crystal grain that Xiamen Golden Egret Special Alloy Co., Ltd produces is the thin tungsten carbide powder of 0.8 μm, crystal grain is the thin cobalt powder of 0.8 μm, according to the proportioning of WC-10.3wt.%Co, make medium with raw spirit and carry out wet-milling in roller ball mill, ratio of grinding media to material is 4:1, liquid-solid ratio is 250mL/kg, and ball milling 48h final vacuum is dry, obtains WC-10.3wt.%Co compound.
(2) dry after dried WC-10.3wt.%Co compound being mixed the paraffin of 2wt.%, then cross 80 eye mesh screens, granulate, make compound have certain mobility.
(3) the granulation compound obtained in step (2) is pressed into pressed compact, pressing pressure is 15MPa.
(4) by Cr 2c 3with alcohol, water, polyoxyethylene glycol is mixed with the grain inhibitor solution of 0.6g/ml.
(5) solution configured in step (4) is spread upon pressed compact surface prepared in step (3).
(6) sintered under vacuum by the pressed compact being coated with grain inhibitor in step (5), sintering temperature controls at 1420 DEG C, and soaking time is 2h, and the heat-up rate wherein between 950 ~ 1150 DEG C is 2 DEG C/min then furnace cooling.
Quantitative assay for constituent content in sample uses EPMA (JXA-8530F, JEOL) point analysis (radius: 50 μm) in is to Co, the content of Cr is analyzed, measurement range is grain inhibitor attachment surface extremely distance grain inhibitor attachment surface 6mm place, is spaced apart 0.5mm.Hardness test adopts dimension formula hardness test, and test specification is the same.The measurement of mean grain size adopts the testing method specified in ISO4499, measures the crystal grain of more than 250.
The gradient layer of the WC-Co granular gradient alloy adopting above-mentioned technique to prepare is about 4.5mm, its Cr 2c 3the microstructure of attachment surface is shown in accompanying drawing 5, and the mean grain size of its WC is about 0.64 μm, apart from Cr 2c 3the microstructure at attachment surface 6mm place is shown in accompanying drawing 6, and the mean grain size of its WC is about 0.89 μm.Apart from Cr 2c 3the mean grain size at attachment surface 6mm place is about Cr 2c 31.4 times of attachment surface.Cr 2c 3the dimension formula hardness of attachment surface is 1627Hv1, apart from Cr 2c 3the dimension formula hardness at attachment surface 6mm place is 1515Hv1, and the hardness of attachment surface is about 1.073 times of 6mm place.From Cr 2c 3attachment surface is to distance Cr 2c 3attachment surface 6mm place's changes in hardness and Cr/Co value are shown in accompanying drawing 7.Co content is from Cr 2c 3attachment surface is to distance Cr 2c 3accompanying drawing 8 is shown in the change at attachment surface 6mm place.
Embodiment three
(1) the RTP compound of the WC-6wt.%Co selecting Xiamen Golden Egret Special Alloy Co., Ltd to produce.
(2) the granulation compound obtained in step (1) is pressed into pressed compact, pressing pressure is 15MPa.
(3) by Cr 2c 3with alcohol, polyoxyethylene glycol is mixed with the grain inhibitor solution of 0.5g/ml.
(4) solution configured in step (3) is spread upon pressed compact surface prepared in step (2).
(5) pressed compact being coated with grain inhibitor in step (4) is sintered under vacuum, sintering temperature controls at 1460 DEG C, soaking time is 1h, and the heat-up rate wherein between 1000 ~ 1200 DEG C is 2 DEG C/min, then furnace cooling.
Quantitative assay for constituent content in sample uses EPMA (JXA-8530F, JEOL) point analysis (radius: 50 μm) in is to Co, the content of Cr is analyzed, measurement range is grain inhibitor attachment surface extremely distance grain inhibitor attachment surface 6mm place, is spaced apart 0.5mm.Hardness test adopts dimension formula hardness test, and test specification is the same.The measurement of the mean grain size of WC adopts the testing method specified in ISO4499, measures the crystal grain of more than 250.
The gradient layer of the WC-Co granular gradient alloy adopting above-mentioned technique to prepare more than 6mm, its Cr 2c 3the microstructure of attachment surface is shown in accompanying drawing 9, and the mean grain size of its WC is about 0.80 μm, apart from Cr 2c 3the microstructure at attachment surface 6mm place is shown in accompanying drawing 10, and the mean grain size of its WC is about 1.11 μm.Apart from Cr 2c 3the mean grain size at attachment surface 6mm place is about Cr 2c 31.39 times of attachment surface.Cr 2c 3the dimension formula hardness of attachment surface is 1730Hv1, apart from Cr 2c 3the dimension formula hardness at attachment surface 6mm place is 1630Hv1, and the hardness of attachment surface is about 1.061 times of 6mm place.From Cr 2c 3attachment surface is to distance Cr 2c 3attachment surface 6mm place's changes in hardness and Cr/Co value are shown in accompanying drawing 11.Co content is from Cr 2c 3attachment surface is to distance Cr 2c 3accompanying drawing 12 is shown in the change at attachment surface 6mm place.
The adhering mode of grain inhibitor is changed to liquid attachment by the present invention, makes it can be applied to more shape.Traditional High temperature diffusion is changed to the mode that low temperature osmotic and High temperature diffusion combine by the present invention, the temperature and time of one-step optimization High temperature diffusion of going forward side by side.About low temperature osmotic, because containing water in the mixed solution of grain inhibitor, alcohol, the materials such as polyoxyethylene glycol, can and green compact in paraffin produce dissolving to a certain extent, thus make grain inhibitor element from attachment surface to internal diffusion in room temperature or the lower temperature region in sintering.About temperature and the optimization of High temperature diffusion, between its best spreading area, heat-up rate is slowed down for different grain inhibitor elements, increase its diffusion time, promote the internally low concentration region diffusion from high surface levels region further of grain inhibitor element, and make it even at short range wireless internal diffusion.The present invention uses moisture, alcohol, and one or more solvents in polyoxyethylene glycol, as the one of the composition of mixing attachment liquid, avoid the generation of Co gradient.
Above-described embodiment is only used for further illustrating standby granular gradient Wimet of a kind of liquid infiltration legal system of the present invention and preparation method thereof; but the present invention is not limited to embodiment; every above embodiment is done according to technical spirit of the present invention any simple modification, equivalent variations and modification, all fall in the protection domain of technical solution of the present invention.

Claims (7)

1. with the granular gradient Wimet that liquid infiltration legal system is standby, it is characterized in that: comprise WC and Co, wherein, Co content accounts for the 3.wt% ~ 20.wt% of WC and Co total amount; Also comprise containing Cr, V, Ta, Nb, Ti, Zr, one or more grain inhibitor elements in Hf, Mo, and the concentration of contained element is progressively reduce from described alloy surface to core, its surface concentration is not higher than the 1wt.% of WC, Co and contained element total amount, and its core concentration is minimum can be 0wt.%; The WC mean grain size of described alloy is in increasing gradually from top layer to core, and the mean grain size of its core is 1.05 ~ 1.5 times of surface.
2. the granular gradient Wimet that liquid infiltration legal system according to claim 1 is standby, it is characterized in that: the hardness of described alloy shows as from surface to core in reducing gradually, its surface hardness is 1.03 ~ 1.2 times of core, and the hardness of alloy shows as there is not Co gradient from surface to core.
3. the granular gradient Wimet that liquid infiltration legal system according to claim 2 is standby, is characterized in that: described top layer is the region that the grain inhibitor of span sample is coated with that the distance of wiping one's face is no more than 100 μm; Described core refers to that the ratio of contained constituent content and Co content is the region of contained element/Co<0.75%, or is coated with the distance of the wiping one's face region more than 6mm apart from grain inhibitor.
4. the granular gradient Wimet that liquid infiltration legal system according to claim 3 is standby, it is characterized in that: the surface of described alloy is granular gradient layer to the region between core, the contained constituent content in this region and the ratio of Co content are element/Co<10% contained by 0.75%<.
5., by a preparation method for the standby granular gradient Wimet of liquid infiltration legal system, it is characterized in that: comprise the steps:
A. raw material is chosen:
WC powder: be the WC powder of single mean particle size;
Co powder: be the Co powder of single mean particle size;
Forming agent: be paraffin, polyoxyethylene glycol.
Grain inhibitor: containing carbide or the oxide compound of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo;
B. compound preparation: the required mixed powder of 3.wt% ~ 20.wt% preparation accounting for WC and Co total amount according to Co content, WC-Co compound is prepared after wet-milling, drying process, wherein, the forming agent of the 1 ~ 2wt.% accounting for WC, Co and forming agent total amount is mixed before wet-milling or after wet-milling;
C. green compact preparation: the green compact according to the requirement preset, compound being pressed into required shape;
D. grain inhibitor mixed solution preparation: will containing the carbide of one or more grain inhibitor elements in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo or the powder of oxide compound and water, alcohol, in polyoxyethylene glycol, one or more solvent prepare grain inhibitor mixed solution.Wherein containing the carbide of one or more grain inhibitor elements or the proportional range of oxide compound and solution in Cr, V, Ta, Nb, Ti, Zr, Hf, Mo is 0.1 ~ 1.5g/ml;
E. adhere to: the region needing to realize granular gradient grain inhibitor mixed solution prepared in step D being applied to the green compact prepared by step C;
F. sinter: the green compact being coated with grain inhibitor are carried out high temperature sintering process, thus obtain granular gradient Wimet.
6. the preparation method of the granular gradient Wimet that liquid infiltration legal system according to claim 5 is standby, it is characterized in that: described high temperature sintering process sinters under vacuum, wherein, heat-up rate between 900 ~ 1280 DEG C is not higher than 2 DEG C/min, sintering temperature controls at 1320 ~ 1550 DEG C, soaking time controls at 0.5 ~ 4h, and sintering oven internal pressure remains on 60 ~ 2000Pa.
7. the preparation method of the granular gradient Wimet that liquid infiltration legal system according to claim 5 is standby, it is characterized in that: described high temperature sintering process sinters under overpressure condition, heat-up rate wherein between 900 ~ 1280 DEG C is not higher than 2 DEG C/min, sintering temperature controls at 1320 ~ 1550 DEG C, soaking time controls at 0.5 ~ 4h, and in sintering oven, Ar gas dividing potential drop remains on 0.5 ~ 9.5MPa.
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CN107405687A (en) * 2015-04-24 2017-11-28 哈利伯顿能源服务公司 The method for making ceramics or intermetallic compound part
CN107435147A (en) * 2016-05-26 2017-12-05 肯纳金属公司 Product and its application with covering
CN111069610A (en) * 2019-12-20 2020-04-28 株洲硬质合金集团有限公司 Hard alloy spherical tooth with gradient structure and preparation method thereof
US11566718B2 (en) 2018-08-31 2023-01-31 Kennametal Inc. Valves, valve assemblies and applications thereof

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Publication number Priority date Publication date Assignee Title
CN107405687A (en) * 2015-04-24 2017-11-28 哈利伯顿能源服务公司 The method for making ceramics or intermetallic compound part
CN107435147A (en) * 2016-05-26 2017-12-05 肯纳金属公司 Product and its application with covering
CN107435147B (en) * 2016-05-26 2021-10-15 肯纳金属公司 Coated article and use thereof
CN106702249A (en) * 2016-12-12 2017-05-24 南京航空航天大学 Preparation method of WC-Co hard alloy of gradient structure
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US11566718B2 (en) 2018-08-31 2023-01-31 Kennametal Inc. Valves, valve assemblies and applications thereof
CN111069610A (en) * 2019-12-20 2020-04-28 株洲硬质合金集团有限公司 Hard alloy spherical tooth with gradient structure and preparation method thereof

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