A kind of preparation method of nanometer tungsten carbide/Co composite powder
Technical field
The present invention relates to a kind of preparation technology of nanostructured tungsten carbide/cobalt composite powder, especially a kind of scale industrialization preparation of multiduty nanostructured tungsten carbide/cobalt composite powder is related to, be mainly used in the preparation of ultra-fine nano-powder, particularly the preparation technology of nanometer tungsten based composite powder series material and method field.
Background technology
Refractory metal tungsten alloy has the physical and mechanical property of a series of excellence, has purposes very widely, occupy an important position in national economy in the fields such as defence and military, Aero-Space, electronic information, the energy, metallurgy and Mechanical Processing Industry.The wearability that W-Co carbide alloy has high hardness, intensity is become reconciled, is that one is only second to adamantine hard material, is widely used as machining instrument, be called as " tooth of modern industry ".Thus such alloy material receives the great attention of countries in the world, has become one of research field that material supply section educational circles enlivens the most.
Along with the development that science and technology is maked rapid progress, also more and more high to the requirement of material; Adapt with it, to employ new technology and novel preparation process is the developing direction of the multi-functional tungsten sill of research and development novel high-performance.Because nano material has the incomparable property of many traditional materials, it is made to become one to the promising research direction of raising material property most.
Traditional cemented carbide powder production procedure: ammonium paratungstate (APT)-WO
3-W-WC-batching-shaping--sintering, technical process is various, and each operation has the possibility making contaminated and dirtyization of raw material, and repeatedly repeatedly pyroprocess the grain size of final products can be made wayward, wherein WO
3reduction and carbonisation, prepare burden mechanical milling process and sintering process all need to consume a large amount of energy, this not only makes, and the production cycle of carbide alloy series of products is elongated, product quality is wayward, also makes production cost and energy consumption become very high.
CNT (CNT) has very high Young's modulus, and has very high thermal conductivity, electrical conductivity and chemical inertness.CNT (CNT) is added in matrix material or coating and forms new composite, mechanics and the electric property of composite can be improved significantly.Nano powder of tungsten carbide then with the dual good characteristic of superhard material and nano particle, if can with CNT (CNT) compound use, extremely far-reaching influence will be produced to field of new.
Various superfines preparation method and technology being are all are being researched and developed energetically so that develop more high performance Hardmetal materials further in current countries in the world.Wherein superfine nano structure WC-Co composite powder end and coating material high-performance preparation technology in more increase fund input and technical research dynamics, developed the process that some prepare nanometer WC-Co composite powder.
At present, the preparation technology of WC-Co dusty material mainly contains:
(1), use fixed bed or rotary furnace etc. to be reduced in a hydrogen atmosphere by the oxide of tungsten and become high purity tungsten, obtained high purity tungsten and carbon dust are carried out mixing and ball milling, eventually pass high temperature cabonization and can obtain WC powder, WC powder and metal Co powder Homogeneous phase mixing are carried out mechanical ball milling and can prepare WC-Co powder; Or make the oxide of tungsten mutually mix with carbon dust, and by direct-reduction carbonization in rotary furnace hydrogen atmosphere under the high temperature conditions, can obtain WC powder, WC powder carries out ball milling thus obtained WC-Co powder with the mixing of metal Co powder again.
The method is the preparation method of traditional WC-Co hard alloy powder, and the shortcoming of this conventional method is that W and Co mixing is uneven, and carburizing temperature is high and energy consumption is high, is difficult to prepare nano level super fine composite powder.
(2), a kind of preparation method of nanometer WC-Co composite powder is mentioned in the patent of invention (patent No. ZL 97106622.1) of the people such as Zhang Zongtao, with water miscible tungstenic, cobalt salt class and macromolecular organic compound prepare precursor solution as reaction raw materials jointly, can chemical reaction be there is thus generate sediment in precursor solution, the sediment surface formed is coated with the hydrophobic film layer of one deck paraffin class, and by reducing agent as inferior sodium phosphate etc. removes wherein moisture and other organic groups, finally formed only containing tungsten, cobalt, the mixture of carbon, this mixture just can be obtained nanometer WC-Co composite powder through carbonization treatment.
This technique is owing to employing a large amount of macromolecular organic compounds and reducing agent, so technical process is relatively stricter to the requirement of production equipment, and the purity of product is difficult to control.
(3), first the raw material spraying dry of tungstenic cobalt is made the composite oxide power of tungstenic, cobalt element, more obtained tungsten cobalt/cobalt oxide powder is put into fluidized-bed reactor, at certain temperature conditions and H
2/ CO/CO
2carry out continuous reduction and carbonization reaction in atmosphere, WC-Co composite powder end can be obtained.Or tungsten cobalt compound and grain growth inhibitor are prepared the powder of composite oxides via spray pyrolysis, by this composite oxide power in a fluidized bed reactor, nano-structure WC-Co composite powder is prepared through techniques such as reduction and carbonization, supplementary carbonization and tune carbon.
The method production cost is high, the more difficult control of technical process.
(4), jointly mixed solution is made by tungstenic salt with containing cobalt salt class, mixed solution carries out spray-drying process in the spray drying tower can obtain composite oxide power presoma, this precursor powder carries out ball milling with carbon dust mixing after calcining, in hydrogen atmosphere, finally carries out reduction and carbonization just can obtain nanoscale WC-Co composite powder end.
The method employs hydrogen atmosphere and carbon dust mixing and ball milling in reduction and carbonization technique, makes the carbon content of the composite powder prepared wayward.And there is tungsten oxide and cobalt oxide in this process, thus can hydrate be generated in redox reaction, particle finally can be made to be easy to agglomeration.
Summary of the invention
The invention solves deficiency in prior art and technique and defect and to provide a kind of process route easy, by adding CNT (CNT) to water-soluble tungsten salt, water soluble cobaltous salt, water-soluble carburizing nodulizer and Water Soluble Compound grain growth inhibitor mixed aqueous solution, the new technology that scale industrialization prepares ultrafine gain size nanostructured superfine WC-Co composite powder body material can be realized.
For realizing above object, the present invention by the following technical solutions: a kind of preparation method of nanometer tungsten carbide/Co composite powder, is characterized in that comprising following processing step:
Step 1: be the water-soluble tungsten salt of 55-92% by mass fraction percentage, to be dissolved in quality be in 3-5 water doubly to the Water Soluble Compound grain growth inhibitor of the water soluble cobaltous salt of 3-40%, the water-soluble carburizing nodulizer of 3-6% and 0.1-2%, is mixed with mixed aqueous solution;
Step 2: the CNT (CNT) adding step 1 aqueous solution gross mass 1%-10% in the mixed aqueous solution that step 1 obtains, stirs 30 ~ 60 minutes with the speed of 10 ~ 30 revs/min, can mix;
Step 3: by the mixed aqueous solution that obtains in step 2 through fast low temperature spraying dry, described low temperature drying intake air temperature is 150 ~ 200 DEG C, and air outlet temperature is only 70 ~ 90 DEG C, can obtain ultrafine tungsten cobalt complex salt precursor powder;
Step 4: the presoma powder obtained in step 3 carried out under 900-1000 DEG C of temperature conditions reduction synthesis and adjust carbon, preparing the tungsten carbide/cobalt composite powder material with nanostructured.
Under better status of implementation, described water-soluble tungsten salt adopts ammonium metatungstate (AMT) or ammonium paratungstate (APT) one wherein or its mixture.
Under better status of implementation, described water soluble cobaltous salt is Co (NO3)
2, cobalt acetate, cobalt oxalate or CoCl
2wherein one or more mixing.
Under better status of implementation, described water-soluble carburizing nodulizer comprises one in polyethylene glycol (PEG), polyvinyl alcohol (PVA), starch, sugar or two or more high-molecular organic adhesive mixes mutually.Water-soluble carburizing nodulizer plays reduction and carburization in the reduction, carbonisation of powder, and another effect increases solution viscosity, improves Surface Tension of Liquid Drops, is convenient to manufacture spherical powder.
Under better status of implementation, described Water Soluble Compound grain growth inhibitor is water-soluble chromic salts or vanadic salts.
Under better status of implementation, in the aqueous solution of described step 2, be added with the CNT (CNT) of 3%-8%.
Under better status of implementation, described step 4 using hydrogen as reduction protection atmosphere, with methane or CO/CO
2for carbon potential atmosphere, under the hot conditions of 900-1000 DEG C, carry out reduction synthesis and adjust carbon.
The present invention has following beneficial effect:
1, (ammonium metatungstate (AMT) or ammonium paratungstate (APT) are as fundamental reaction raw material and carried out the preparation of nano composite powder by solwution method, avoid the many unfavorable factors produced to the conventional method preparing superfines because generally using all solid state material to carry out mixing and ball milling at present to use the tungsten/cobalt salt class of highly-water-soluble; The composite grain that same employing has a highly-water-soluble is grown up inhibitor, creative compared with directly adding the process of solid-state inhibitor before.
2, described preparation technology uses highly-water-soluble tungsten salt, cobalt salt as primitive reaction raw material, the composite grain added in addition inhibitor of growing up also is water miscible, carbon source also adopts liquid carbon source, reaction is carried out more abundant, powder grain obtains further refinement, creative compared with directly adding the process of solid-state inhibitor before.
3, described water-soluble carburizing nodulizer comprises one in polyethylene glycol (PEG), polyvinyl alcohol (PVA), starch, sugar or two or more high-molecular organic adhesive mixes mutually.Described water-soluble carburizing nodulizer plays reduction and carburization in the reduction, carbonisation of powder, and another effect increases solution viscosity, improves Surface Tension of Liquid Drops, is convenient to manufacture spherical powder.Described water-soluble carburizing nodulizer can reduce processing cost and effective protection of the environment, meets the construction of resource-efficient and environment friendly society.
4, in primitive reaction raw material, with the addition of appropriate CNT (CNT), multiduty superfine nano WC/Co composite powder can be prepared, make product have the dual good characteristic of CNT (CNT) and nanometer tungsten carbide simultaneously, of many uses.In raw materials technology, add CNT (CNT) is another innovative point of the present invention.This technique can produce nanometer tungsten carbide-CNT (CNT) composite powder material; Current this composite powder material is mainly used in the modification of composite deposite technology.Single use nano powder of tungsten carbide or CNT (CNT) all can weaken the integrated application performance of composite deposite to a certain extent; As merely by the variation that may cause ductility of electrodeposited film during the wild phase of nano tungsten carbide as composite deposite, otherwise, use equally merely CNT (CNT) greatly to aggravate as the wearing and tearing of coating can be made during composite deposite wild phase, CNT (CNT) and nanometer tungsten carbide uses jointly time then significantly can improve the bulk strength of coating, toughness and coefficient of friction.
5, in the preparation technology of above-described nano composite powder, mixed aqueous solution uses spray drying tower to carry out drying and granulating to obtain complex salt precursor powder, uses elevated-temperature seal fluidization synthetic furnace to carry out last carbonizing reduction treatment process.
6, can excessive grain be effectively stoped to overgrow owing to adding grain growth inhibitor in step 1 in reaction raw materials, thus control grain refinement, the grain graininess of goods and distribution thereof, therefore the kind of crystallizing inhibitor select, addition manner and the raising of interpolation time to properties of product most important.In technical scheme proposed by the invention, abandon the interpolation using method of traditional solid-state crystallizing inhibitor, and creationary employing water miscible compound crystallizing inhibitor (comprise water-soluble vanadic salts/chromic salts, as ammonium dichromate, ammonium metavanadate, VC/Cr
3c
2or V
2o
5/ Cr
3o
5deng), make grain growth inhibitor can evenly be diffused between each crystal grain, be present between crystal boundary or be dissolved in Binder Phase, thus more effectively can stop grain growth, making crystal grain obtain further refinement.
7, use the nanostructured tungsten carbide/cobalt composite powder prepared by above-mentioned technique to have particle size distribution narrow range, regular shape, uniformity and good fluidity, crystal grain is tiny, the mean grain size feature such as between 40 ~ 60nm.
In sum, the present invention is that a kind of process route is simple, and properties of product are excellent, product granularity is even and crystal grain is tiny, are applicable to very much the preparation method of the nano-structure WC-Co composite powder carrying out industrialization large-scale production.
Accompanying drawing explanation
Fig. 1 is preparation technology's flow chart of the present invention.
Detailed description of the invention
Below in conjunction with the drawings and specific embodiments, the present invention is explained the most further.
Example 1:
Step 1: by the ammonium metatungstate (AMT) of 55kg, the Co (NO3) of 40kg
2, to be dissolved in quality be in the water of 300kg for the polyethylene glycol (PEG) of 3kg and the water-soluble vanadic salts of 2kg, is mixed with mixed aqueous solution;
Step 2: the CNT (CNT) adding 1kg in the mixed aqueous solution that step 1 obtains, stirs 30 minutes with the speed of 10 revs/min, can mix;
Step 3: by the mixed aqueous solution that obtains in step 2 through fast low temperature spraying dry, described low temperature drying intake air temperature is 150 DEG C, and air outlet temperature is only 70 DEG C, can obtain ultrafine tungsten cobalt complex salt precursor powder;
Step 4: the presoma powder obtained in step 3 carried out under 900 DEG C of temperature conditions reduction synthesis and adjust carbon, preparing the tungsten carbide/cobalt composite powder material with nanostructured.
The mean grain size of tungsten carbide/cobalt composite powder material is obtained between 50 ~ 60nm by example 1.
Example 2:
Step 1: the water-soluble vanadic salts of the cobalt oxalate of the ammonium paratungstate (APT) of 92kg, 3kg, the polyvinyl alcohol (PVA) of 3kg and 2kg is dissolved in the water of 400kg, is mixed with mixed aqueous solution;
Step 2: the CNT (CNT) adding 3kg in the mixed aqueous solution that step 1 obtains, stirs 40 minutes with the speed of 20 revs/min, can mix;
Step 3: by the mixed aqueous solution that obtains in step 2 through fast low temperature spraying dry, described low temperature drying intake air temperature is 200 DEG C, and air outlet temperature is only 90 DEG C, can obtain ultrafine tungsten cobalt complex salt precursor powder;
Step 4: the presoma powder obtained in step 3 carried out under 900 DEG C of temperature conditions reduction synthesis and adjust carbon, preparing the tungsten carbide/cobalt composite powder material with nanostructured.
The mean grain size of tungsten carbide/cobalt composite powder material is obtained between 45 ~ 55nm by example 2.
Example 3:
Step 1: by the ammonium paratungstate (APT) of 62kg, the CoCl of 30kg
2, the starch of 6kg and the water-soluble chromic salts of 2kg be dissolved in the water of 500kg, is mixed with mixed aqueous solution;
Step 2: the CNT (CNT) adding 8kg in the mixed aqueous solution that step 1 obtains, stirs 60 minutes with the speed of 30 revs/min, can mix;
Step 3: by the mixed aqueous solution that obtains in step 2 through fast low temperature spraying dry, described low temperature drying intake air temperature is 180 DEG C, and air outlet temperature is only 80 DEG C, can obtain ultrafine tungsten cobalt complex salt precursor powder;
Step 4: the presoma powder obtained in step 3 carried out under 1000 DEG C of temperature conditions reduction synthesis and adjust carbon, preparing the tungsten carbide/cobalt composite powder material with nanostructured.
The mean grain size of tungsten carbide/cobalt composite powder material is obtained between 40 ~ 50nm by example 3.
Example 4:
Step 1: by the water-soluble chromic salts of 70kg ammonium paratungstate (APT), the cobalt acetate of 25kg, the sugar of 4.9kg and 0.1kg be dissolved in the water of 400kg, be mixed with mixed aqueous solution;
Step 2: the CNT (CNT) adding 10kg in the mixed aqueous solution that step 1 obtains, stirs 60 minutes with the speed of 30 revs/min, can mix;
Step 3: by the mixed aqueous solution that obtains in step 2 through fast low temperature spraying dry, described low temperature drying intake air temperature is 200 DEG C, and air outlet temperature is only 70 DEG C, can obtain ultrafine tungsten cobalt complex salt precursor powder;
Step 4: by the presoma powder that obtains in step 3 using hydrogen as reduction protection atmosphere, with methane or CO/CO
2for carbon potential atmosphere, under 900 DEG C of temperature conditions, carry out reduction synthesis and adjust carbon, preparing the tungsten carbide/cobalt composite powder material with nanostructured.
The mean grain size of tungsten carbide/cobalt composite powder material is obtained between 40 ~ 50nm by example 4.
Example 5:
Step 1: by the ammonium metatungstate (AMT) of 65kg, the CoCl of 30kg
2, polyethylene glycol (PEG) and starch mixture 4kg and 1kg water-soluble vanadic salts be dissolved in the water of 500kg, be mixed with mixed aqueous solution;
Step 2: the CNT (CNT) adding 7kg in the mixed aqueous solution that step 1 obtains, stirs 50 minutes with the speed of 20 revs/min, can mix;
Step 3: by the mixed aqueous solution that obtains in step 2 through fast low temperature spraying dry, described low temperature drying intake air temperature is 180 DEG C, and air outlet temperature is only 80 DEG C, can obtain ultrafine tungsten cobalt complex salt precursor powder;
Step 4: by the presoma powder that obtains in step 3 using hydrogen as reduction protection atmosphere, with methane or CO/CO
2for carbon potential atmosphere, under 900 DEG C of temperature conditions, carry out reduction synthesis and adjust carbon, preparing the tungsten carbide/cobalt composite powder material with nanostructured.
The mean grain size of tungsten carbide/cobalt composite powder material is obtained between 40 ~ 50nm by example 5.
Preparation technique and the process of this superfine nano multiple tungsten carbide/cobalt conjunction powder have creativeness as described below, are that those skilled in the art are non-obvious.According to above embodiment, draw to draw a conclusion:
(1) production technology of the domestic Solid raw materials mixing and ball milling method generally adopted before, is fully changed, but adopt full water-soluble tungsten/cobalt salt class raw material to carry out solution mixing method, to reach the mutual mixing of multicomponent on ion concentration, thus realize the object of powder preparation liquefied, distributed components, component formation Composite.
(2) in raw material, with the addition of appropriate CNT (CNT), innovatively, make dispersedly in the nano composite powder produced have a certain amount of CNT (CNT); This new technology not only can prepare the nanometer WC-Co composite powder of ultrafine gain size, simultaneously output can also can be used for nanometer tungsten carbide-CNT (CNT) the composite deposite modified powder material of composite deposite modification technology; This material has the dual premium properties of nanometer tungsten carbide and CNT (CNT) simultaneously, greatly can strengthen bulk strength and the toughness of coating material.
(3), abandon the Mechanical Crushing method such as the consistent pressed powder mutual mixed grinding crush method that uses or mechanical attrition method at present, adopt solwution method also through high-pressure fog rapid draing, the nanometer refinement to powder grain can be realized;
(4), the aging method that traditional use fixed bed carries out reduction and carbonization is changed completely, the use elevated-temperature seal fluidization synthetic furnace of novelty carries out reduction and carbonization operation, impel powder more to disperse and give full play to the effect of grain growth inhibitor, the contact preventing powder mutual is grown up and intergranular bonding, reunion.
(5), change before use hydrogen atmosphere reducing process, and adopt activated carbon to carry out reduction reaction, so the hydrate of tungsten can not be produced, the deposition of powder grain can be effectively suppressed to be grown up, and the gas carburization of powder surface carries out with inner in-situ carburization is simultaneously two-way, greatly accelerate carburizing reagent speed, reduce cost.
The technology of preparing of this nanostructured composite granule and process thereof can realize low input, prepare nano combined tungsten carbide/cobalt dusty material to extensive industrialization; The composite granule good fluidity produced, particle size distribution is narrow, and pattern rule, crystal grain is tiny.
Above the preparation method of a kind of nanometer tungsten carbide/Co composite powder provided by the present invention is described in detail, set forth principle of the present invention and embodiment herein, the explanation of above embodiment just understands method of the present invention and core concept thereof for helping; Meanwhile, for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.