Hard alloy substrate complex shaped cutter diamond coatings preparation method
Technical field
The present invention relates to a kind of diamond-coated tools preparation method, the compound preconditioning technique of particularly a kind of employing microwave chemical and electronics strengthen hot-wire chemical gas-phase deposition (CVD) method the hard alloy substrate complex shaped cutter are carried out the preparation method of diamond coatings, belong to technical field of mechanical cutting tool manufacture.
Background technology
Chemical vapor deposition (CVD) diamond coatings technology can effectively be carried out coating to complex shaped cutter, thereby raising tool life, reduce production costs, application prospect is very extensive, so the Application and Development of complicated shape diamond-coated tools is CVD diamond coatings technology real advantage place.Yet, because the constructional feature of complex shaped cutter and the requirement of use properties, the sticking power of diamond thin behind cutter matrix surface pretreatment technology, deposition apparatus and depositing operation, the heavy film and tool matrix detected to estimate etc. all its singularity, makes that complicated shape diamond-coated tools realization industrialization difficulty is very big.Find that according to actual cut processing there are two big obstacles in coated cutting tool in actual cut is used, the one, the coatings prepared adhesion strength is on the low side; The 2nd, the coatingsurface roughness is higher.And the adhesion strength of coating and surfaceness thereof are two key factors that influence coated cutting tool cutting ability quality.Therefore, how when effectively improving coating adhesive strength, to reduce the coatingsurface roughness, it is the key of improving coated cutting tool comprehensive process performance, but the various coated cutting tool preparation methods of research can not address this problem well both at home and abroad at present, and especially the research at complex shaped cutter matrix aspect is almost blank.About on hard alloy substrate, carrying out individual layer nano diamond coating or the research of composite nano-diamond coating technology, also there are not relevant patent and bibliographical information so far both at home and abroad.
Summary of the invention
In order to overcome existing diamond-coated tools preparation method can not effectively reduce the coatingsurface roughness when obtaining high-adhesion deficiency, the invention provides a kind of diamond-coated tools preparation method who adopts compound preconditioning technique of microwave chemical and electronics to strengthen heated filament CVD Nano diamond compound coating technology, this method can not only make coating effectively reduce surfaceness when obtaining high-adhesion, and is not subjected to the restriction of tool matrix shape.Thereby the further promotion and application of coated cutting tool have greatly been promoted.Usually the tool matrix material that is adopted is a Wimet, wherein mainly comprises the wolfram varbide (WC) and cobalt (Co) element mutually that bonds.
The technical solution adopted for the present invention to solve the technical problems is: at first use the compound preconditioning technique of microwave chemical that matrix is carried out pre-treatment, adopt electronics to strengthen heated filament CVD method then, use depositing operation stage by stage, carry out the Nano diamond compound coating.
The compound preconditioning technique concrete steps of microwave chemical are as follows: at first adopt the diamond suspension ultrasonic cleaning that the cutter matrix surface is carried out purifying treatment to remove the oil stain dirt on cemented carbide with complicated shape tool matrix surface, then through the microwave oxide treatment, generate the oxide compound of cobalt on the tool matrix surface, through follow-up basic solution chemical treatment, the oxide compound of cobalt surface is thoroughly removed.Remove the trace cobalt element that the surface appears again with the acid solution ultrasonic cleaning with thorough again.By above processing, both removed the cobalt of upper layer up hill and dale, eliminate of the influence of top layer cobalt to diamond film, keep the cobalt of deep layer again, toughness and the intensity to tool matrix does not cause damage.Chemical reaction all carries out at the WC particle interface, and WC particle is appeared, thereby produces the microcosmic injustice, and the alligatoring effect is obvious.Carry out microwave decarburization reduction at last and handle, with hydrogen (H
2) make the WC of matrix surface that decarburization take place with the mixed gas (hydrogen/argon gas) of argon gas (Ar), WC particle is reduced into tiny and fine and close W, so that at the initial stage of depositing diamond, and carbon in the reactant gases and the tiny WC of matrix surface W generation chemical bonding regeneration.Tiny and fine and close WC makes diamond crystal forming core density increase substantially, simultaneously also between the diamond multicrystal film of subsequent growth and cutter original substrate, form the nature transition layer, help cushioning thermal stresses, cobalt surface is removed and makes that in the micro-space that the surface stays between sedimentary diamond of institute and the matrix surface WC material mechanicalness taking place inlays, and all of these factors taken together all helps increasing substantially the adhesion strength of diamond coatings.
It is as follows that electronics strengthens heated filament CVD Nano diamond compound coating technology concrete steps: take off cobalt, decarburization and to after the matrix surface roughening treatment, adopt electronics to strengthen heated filament CVD method by the pre-treatment of chemical microwave compound surface, tool matrix is carried out coating.In the diamond coatings starting stage, by selecting suitable processing parameter improving diamond crystal forming core density, for the growth of well-crystallized's diamond multicrystal film provides primary condition; In the diamond coatings intermediate stage, by technological measures such as control depositing temperature, reaction pressures, crystal grain is sturdy to grow, the diamond multicrystal film of good crystallinity, be beneficial to improve coating adhesive strength, improve diamond coatings quality and wear resistance, but this moment diamond multicrystal film surface irregularity, diamond crystal is of a size of 1~5 micron; In the diamond coatings later stage, the CVD novel process that adopt to increase secondary nucleation promptly: take to reduce air pressure, increase carbon source concentration and add technological measures such as argon gas, greatly improve diamond second nucleation rate.Growth in situ one deck is assembled the spherical nano-diamond film that forms by crystallite again on the diamond multicrystal film of the good crystallinity of having grown, nanocrystal size is 10~50 nanometers, sedimentary compound coating has advantages such as adhesion strength height, smooth surface, frictional coefficient be low simultaneously, can remove the grinding and polishing operation from.Nano diamond compound coating technology is not only applicable to the preparation of blade, and more is applicable to the preparation of monoblock type rotary cutter.On the basis that obtains high-adhesion, fully can be on the order of magnitude of Ra≤0.4 micron with the diamond coatings Roughness Surface on Control, reach abrasive levels, satisfy the requirement of high speed cutting high adhesion strength of diamond-coated tools and low surfaceness.
The invention has the beneficial effects as follows, can when obtain high-adhesion, reduce the coatingsurface roughness easily, thereby greatly improve the cutting ability of coated cutting tool.And this method is not subjected to the restriction of base shape, is applicable to the coating preparation of any complex shaped cutter matrix.And the inventive method is simple to operate, it is convenient to use, can be with higher deposited at rates large-area diamond nano-composite coating, and industrialization prospect light has remarkable economic efficiency.
Embodiment
Below in conjunction with being the preparation example that matrix carries out the Nano diamond compound coating, concrete enforcement of the present invention is further described with the YG serial carbide alloy cutter of selling on the market.
The first step: the inserted tool matrix is put into the ultrasonic cleaning machine that fills diamond suspension, tool matrix is carried out purifying treatment, to remove the oil stain dirt on cemented carbide with complicated shape tool matrix surface.Diamond powder constantly collides matrix surface in ultrasonic, remove the oil stain dirt and the even alligatoring matrix of tool surface, can improve adamantine nucleation density greatly.
Second step: the tool matrix after will handling through the diamond suspension ultrasonic cleaning places the microwave reaction chamber to carry out the microwave oxide treatment.Reactant gases is carbonic acid gas and oxygen, and pressure is 1KPa, and microwave power is about 400W, and substrate temperature is about 900 ℃ during reaction, and the microwave oxidation treatment time is 5~10 minutes.After the microwave oxide treatment, the oxide powder (CoWO of filemot cobalt and tungsten can appear at matrix surface
4And WO
3).
The 3rd step: from the microwave reaction chamber, take out tool matrix after the microwave oxide treatment and place 15% sodium hydroxide (NaOH) solution to carry out the alkaline solution chemical treatment to remove the oxide compound of cobalt surface and tungsten.The color of handling the back matrix surface becomes canescence from tawny, the CoWO that microwave oxidation is at this moment generated
4And WO
3All removed, uniform micro concavo-convex injustice appears in matrix surface, and WC particle manifests the dewiness attitude, and originally the cobalt metal covered of oxide and the compound of cobalt appear again.
The 4th step: will put into the container that fills 10% hydrochloric acid soln through the matrix after the alkaline solution chemical treatment, take out after 2-3 minute, with clear water flush away residual hydrochloric acid, put into again and carry out supersound washing in the ultrasonic cleaning machine that fills diamond suspension, its objective is the cobalt of removing matrix surface, in ultrasonic, constantly collide matrix surface with diamond powder simultaneously,, improve adamantine nucleation density with further even alligatoring matrix.
After the acid solution ultrasonic cleaning was handled, matrix surface composition and structure were returned to virgin state again, but that the surface has produced is equally distributed uneven, and WC particle manifests the dewiness attitude, and the cobalt surface element is effectively checked.This surface treatment result helps the raising of adamantine nucleation of CVD and coating adhesion.
The 5th step: will put in the microwave CVD equipment through the tool matrix after the acid solution ultrasonic cleaning cutter matrix surface is carried out microwave decarburization reduction processing.Make the WC of matrix surface that decarburization take place with hydrogen/argon gas; the carbonization treatment processing parameter is: microwave power 500w, and reaction chamber hydrogen/argon pressure 12Torr is after microwave decarburization in 15 minutes reduction processing; decarburization takes place in the WC of matrix surface, and WC particle is reduced into tiny and fine and close W.
The 6th step: on the compound pretreated basis of above microwave chemical, adopt electronics to strengthen heated filament CVD method again, place electronics to strengthen the CVD reaction chamber tool matrix and carry out conventional diamond coatings.Hot filament adopts the tantalum wire of 0.6 millimeter of φ, and is stretching with high temperature resistant spring, and reaction chamber vacuumizes the back and feeds reactant gases (hydrogen and acetone), and beginning CVD deposits conventional diamond coatings behind the adjustment chamber pressure.Conventional coating process parameter is: pressure 4-10KPa, reactant gases total flux 200-400 ml/min, the volume ratio of acetone/hydrogen (carbon source concentration) is 1-3%, filament temperature is about 2200 ℃, the about 1A of bias current, through 4 hours depositions, the matrix surface deposition obtained the conventional diamond coatings more than 10 microns.
The 7th step: carry out nano diamond coating.After conventional diamond coatings reaches 10 microns, beginning in-situ deposition nano diamond coating.Cutter needn't strengthen the heated filament CVD reaction chamber from electronics and took out this moment, only needed to change processing condition and promptly reduce reaction gas pressure, increased carbon source concentration and had added rare gas element Ar just.Reaction gas pressure can be reduced to 0.5-2KPa, and the carbon source volumetric concentration is increased to 2%-6%, adds argon gas, Ar/H
2Be 0.5-1.5 (volume ratio).Reduce reaction gas pressure, increase carbon source concentration and add the speed that rare gas element has increased the diamond secondary nucleation greatly, deposition has obtained nano diamond coating thus, the about 50-100 nanometer of crystal grain size, coatingsurface is more smooth smooth, and frictional coefficient is little, and hardness also descends to some extent.After 2 hours, obtain thick approximately 5 microns nano diamond coating.Just obtained the Nano diamond compound coating of 15 micron thickness like this in cemented carbide substrate surfaces.