Adamas material polishing method
Technical field
The present invention relates to a kind of Adamas material polishing method.
Background technology
Diamond film is a kind of pleocrystalline, pure polycrystalline diamond, has the fundamental property of natural diamond; Diamond-film-like is meant the amorphous carbon-film that contains diamond lattic structure, and its performance and pure diamond are very approaching.Diamond film and diamond-film-like have very high hardness and wearability, good thermal conductivity, insulating properties, optical characteristics, chemical stability and doping induced semiconductor characteristic etc., as a kind of outstanding structural timber and functional material, prospect has a very wide range of applications in many fields such as decoration, electronics, optics, machinery, optics.Diamond film and diamond-film-like can be because crystal along the preferential growth of some crystal face, causes uneven thickness, granular size not to wait, surface roughness is excessive etc. problem be difficult to directly application in many cases in deposition process.And the hardness height of diamond film and diamond-film-like, stable chemical performance is very easily broken in smooth processing (polishing), so the polishing problem of diamond film and diamond-film-like has become one of its key technologies for application of expansion.
Single-crystal diamond is as a kind of cutter material and special semi-conducting material etc., and its surface finish quality is also most important.
The main finishing method of single-crystal diamond, diamond film and diamond-film-like has at present: mechanical lapping polishing, thermo-chemical polishing, ion beam polishing, laser beam polishing, abrasive water-jet polishing, electro-spark polishing; Pure chemistry polishing, chemical Aided Machine polishing etc.
Traditional machine glazed finish is to adopt bortz powder to add on the metal dish of rotation or adopt skive high speed rotary grinding diamond, and the chemical property of single-crystal diamond, diamond film and diamond-film-like does not take place by significant the variation.Yet polishing and the power that puts on diamond film and the diamond-film-like are easy to produce micro-crack under the surface, and diamond membrane with large area is easy to break.Simultaneously stay the grinding vestige that to eliminate at finished surface easily.The machine glazed finish effect of single-crystal diamond has great relation with the character of polished crystal face.The efficient and the yield rate of machine glazed finish are lower.
Ion beam polishing is inert gas (as the argon gas) ion that utilizes oxygen or big sputtering raste is arranged, and diamond is carried out the ise polishing.The laser beam polishing is to make instantaneous oxidation of diamond or evaporation with laser beam flying diamond surface.These two kinds of processing methods are generally used for the processing of small size film, polishing fair, and apparatus expensive, and operation is had relatively high expectations with control.
The polishing of abrasive particle water jet is that abrasive particle suspension is sprayed to the diamond film surface at a high speed, polishes by the impact and the rubbing action of jet.This method can reach comparatively smooth degree with coarse diamond film surface finish quickly, but the polishing of this method and inhomogeneous, and diamond film had bigger impact, there is microfissure on the surface after the polishing.
Electro-spark polishing diamond film method is by plating the suitable metal of one deck on the diamond film surface, make diamond film become conductor, carry out spark discharge processing then, remove the spike that protrude on the diamond film surface, reach the purpose of polishing, this method needs plated film, has increased the complexity of processing technology, also only is suitable for roughing simultaneously.
By adamantine character as can be known, diamond burns in pure oxygen for 720 ℃, and 850 ℃ burn in air.Utilize adamantine these characteristics, proposed Adamas material polishing methods such as thermochemical method, pure chemistry method, mechanochemical reaction, chemical Aided Machine method.
Thermochemical method is to be in contact with one another with the thermometal plate or metal powder is contacted with diamond film in the mechanical lapping mode as abrasive material by diamond film; Carbon atom in the diamond film is diffused in the thermometal by making, the oxidation of diamond film graphitization and diamond film realizes the removal of diamond film.These metals comprise iron, manganese, magnesium, titanium, aluminium or the like; This method needs the temperature more than 723 ℃; Long processing time, efficient is low, but can realize the highest suface processing quality.
The pure chemistry polishing mainly is to utilize the very strong metal of some chemism such as lanthanum, cerium etc. to make the diamond film surface produce chemical reaction under certain process conditions, thereby the coarse part on diamond film surface is melted eating away.But because the character of chemical reaction process and ablation process itself makes it the surface quality that can not reach very high.
US.Patent 5674107 (J.E.Graebner etc., 1997) has openly reported a kind of diamond film finishing method, uses acidic liquid (H in machine glazed finish
2O
2, HClO, HNO
3, H
2SO
4Deng), add oxide abrasive grain (AgO, KNO
3, CrO
3, MnO
2, BaO
2, PdO
2Lapping liquid Deng forming polishes under the condition of heating; JP2002346915 (high bridge is abundant, 2002) has openly reported a kind of chemical mechanical polishing method, with diamond film by Cr
2O
3, Fe
2O
3The H of abrasive particle
2O
2Or move in the lapping liquid of nitrate composition, because the oxygen of abrasive particle surface enrichment to the oxidation of diamond surface, makes the diamond film rough surface be subjected to the excision polishing.But the machined surface quality of these methods is because the hole that the corrosion of oxide produces is difficult to removal.
Well-known adamantine character shows, diamond diamond when room temperature anti-all acid, alkali and solvent, even when high temperature, and also anti-all acid corrosions.But the corrodible diamond surface of sodium nitrate of fusion in the time of 327 ℃, NaClO
4Deng strong oxidizer can be under lower temperature etching diamond.
A kind of with diamond oxide isolation finishing method (Thornton etc., Polishing diamonds in the presenceof oxidizing agents "; Industrial Review; Supplement; p.39; 1974), under the condition of not using bortz powder, on iron pan, polish natural diamond, added certain density KNO
3Solution by the observation of burnishing surface, is thought chemical reaction between diamond and nitrate to help the coarse unevenness of diamond surface to descend.
The method of machinery and oxidation chemistry polishing diamond (Tribological properties of polished diamondfilms "; Bharat Bhushan et al; J.Appl.Phys.74 (6); p.4174-4180; 1993), two diamond films that all need to polish to be installed face-to-face, a slice maintains static and links to each other with thermal source; another sheet rotates, and two films grind mutually.Between film and film, fill with potassium nitrate (KNO
3) be the chemical oxidizing agent of Main Ingredients and Appearance, diamond film is polished under the acting in conjunction of mechanical lapping and oxide etch.This method equipment requires simple, and the size of film is unrestricted substantially, and polishing efficiency specific heat metal plate method is improved more than the several times.But this method can obtain effect preferably when two films carry out must carrying out a pre-polish(ing) to before grinding; The final roughness of using this kind polishing mode to be obtained is limited.
The method of a kind of machinery and oxidation chemistry polishing diamond (J.Kuehnle, O.Weis.Mechanochemical superpolishing of diamond using NaNO
3Or KNO
3As oxidizing agents.Surface Science, 340, p.16-22,1995) method is with 250-300 ℃ NaNO
3And KNO
3Salt plug is coated in the mill surface continuously and stably, and diamond surface is being polished on salt deposit, and experimental result shows that adamantine polishing efficiency can reach 0.5 μ m/h.Polishing rate is relevant with other burnishing parameters with kind, the high preferred orientation of salt deposit heap(ed) capacity, diamond loaded load, mill speed, salt.
US.Patent 5725413 (Malshe etc., 1998) openly reported the method and apparatus of the leveling and the polishing of a kind of diamond and diamond film, this method is with external force diamond film to be pressed on the polishing disk, simultaneously with KOH, the KNO of diamond film infiltration 380 ℃ molten state
3Or 95: 5 KOH and KNO
3In the mixed liquor, when ceramic polished dishes such as use hardening oxidation aluminium polish diamond film, utilize the KOH and the KNO of molten state
3, the corrosiveness of diamond film is reached the purpose of polishing.Also can add hard particles in the polishing process to improve polishing rate.The polishing velocity of this method will be higher than machine glazed finish or thermo-chemical polishing.But in the time of polishing disk need being heated to more than 380 ℃, just can polish, and realize high like this heating-up temperature at polissoir, simultaneously diamond also must with the polishing disk relative motion, the design and the processing technology of polissoir required than higher.
Summary of the invention
The objective of the invention is the method for machinery and oxidation chemistry polishing diamond material is improved.
Another object of the present invention is to reduce the fusing point that produces the melt substance of chemical reaction with diamond, reduces processing temperature and process equipment complexity.
The present invention also aims to control the distribution of melt substance on polishing disk, change diamond with the melt substance of its generation chemical reaction and the contact condition of polishing disk, produces stable machinery and chemical polishing and processes.
Further purpose of the present invention also is to process ganoid diamond goods.
Adamas material polishing method provided by the invention comprises the steps:
(1) on polishing disk, add salts substances,
(2) with 100~300 ℃ temperature heating polishing disk,
(3) pressure of diamond with 0.2~0.3MP is pressed on the polishing disk,
(4) rotation polishing disk and keep salts substances to contact with diamond makes the diamond surface be flattened and polish.
Polishing disk material of the present invention is cast iron plate or aluminium dish or stainless steel disc, has opened the groove that communicates or do not communicate of some simultaneously on polishing disk, and these grooves make fuse salt be in point, wire on polishing disk; The oxidant of molten state was fully contacted with diamond, again can be so that polishing disk is able to real realization because enough the contact arranged for diamond and polishing disk to the machine glazed finish of diamond.Groove on the polishing disk can also guarantee that fuse salt can be retained in stable flat state, can injustice not occur because of centrifugal force with certain speed rotation polishing disk the time.
Above-mentioned diamond is diamond film, single-crystal diamond or diamond-film-like.
It is KNO that above-mentioned salts substances is formed
3, NaNO
3, LiNO
3, CsNO
3, BaNO
3, LiCL, CaNO
3The salts substances mixture.
Above-mentioned its composition of salts substances mixture is KNO
3, NaNO
3, with CsNO
3, LiNO
3, BaNO
3, LiCL, CaNO
3The various combination mixture.
Use mixed melting salt to make oxidant of the present invention also comprising, reduced the fusing point of fuse salt.
According to existing result of study, normally used oxidant is the highly basic of molten state or nitrate etc.Has the characteristic of fuse salt during these material molten states.Fuse salt is the ion melt; Have excellent conducting performance, its conductance is than the high order of magnitude of electrolyte solution; Have serviceability temperature scope widely, common fuse salt serviceability temperature has relative heat endurance at 300-1000 ℃; Steam forces down, and fuse salt has lower vapour pressure, mixed melting salt particularly, and vapour pressure is lower; Thermal capacity is big; Material there is higher solvability; Viscosity is lower; Has chemical stability etc.
Because the fusing point of one matter is all than higher, such as pure KNO
3Fusing point be 334 ℃, pure NaNO
3Fusing point be 310 ℃, the temperature of mixed melting salt is then much lower, for example the LiNO that adopts of the present invention
3(0.373)+KNO
3(0.449)+NaNO
3(0.178) fusing point of the mixed melting salt of its composition is 120 ℃; KNO
3(0.57-0.60)+LiNO
3(0.43-0.4) fusing point of the mixed melting salt of its composition is 128-134 ℃; CsNO
3(0.24)+KNO
3(0.39)+LiNO
3(0.37) fusing point of its composition is 97 ℃.The ratio of the above-mentioned composition that provides in the bracket is mol ratio.These mixed melting salt and the fusing point thereof that the present invention relates to are specially:
The constitutive molar ratio fusing point (℃)
LiNO
3+KNO
3 0.54∶0.46 193
LiNO
3+KNO
3 (0.43-0.4)∶(0.57-0.60) 128-134
LiNO
3+KNO
3+NaNO
3 0.373∶0.449∶0.178 120
CsNO
3+KNO
3+NaNO
3 0.29∶0.33∶0.38 140
CsNO
3+KNO
3+LiNO
3 0.24∶0.39∶0.37 97
BaNO
3+KNO
3 (0.124-0.133) 287
(0.876-0.867)
BaNO
3+NaNO
3 0.064∶0.936 294-298
BaNO
3+CaNO
3+NaNO
3 0.333∶0.175∶0.492 158
BaNO
3+LiNO
3+NaNO
3 0.013∶0.532∶0.455 214
CaNO
3+NaNO
3 0.310∶0.690 214
LiCl+LiNO
3+NaNO
3 0.05∶0.80∶0.15 174
Our experimental studies results shows, the oxidant KNO during above-mentioned fuse salt of the present invention is formed
3And NaNO
3When it remained on liquid state always, its oxidation was the strongest, and is also the most obvious to the corrosiveness of diamond, and polishing effect also obviously improves.Select suitable oxidant, use cast iron plate and irregular card groove to distribute, select suitable rotating speed and increase pressure all to help improving polishing efficiency.
Our experimental studies results also shows, the oxidation chemistry polishing of diamond is that diamond is under the effect of pressure, its surface is immersed in the oxidant of molten state, oxidant is not only at the surface corrosion diamond, and can enter into the crackle that on diamond, produces because of mechanical friction or because of pressure, react with the diamond of the inside, generate CO and CO
2Thereby diamond is removed.Because the effect of oxidisability salt, diamond also can some change graphite and amorphous carbon into.The laser Raman spectroscopy analysis shows: the diamond surface after the polishing has a small amount of amorphous carbon and graphite.This explanation has a small amount of diamond to change amorphous carbon and graphite in the oxidation chemistry polishing, and diamond must clean after polishing.Polishing disk also can make diamond film and polishing disk contact portion temperature raise except diamond film being had the mechanical polishing action simultaneously, strengthens the activity of oxidant, promotes that amorphous carbon changes to graphite, and will be got rid of by the graphite that diamond generates.
Polishing process of the present invention is, adds an amount of mixing salt in the groove of polishing disk, and polishing disk is heated to the fusing point of salt-mixture, makes its fusing.Diamond is pressed in certain pressure on the polishing disk that has groove, rotates with certain speed by motor band CD; And keep salts substances, polishing disk to contact with diamond; Make the diamond surface be flattened and polish after polishing a period of time.
The invention has the advantages that and use mixed melting salt, adopt the polishing disk that has groove, pass through mechanochemical treatment as oxidant, under lower temperature, improve the diamond polishing efficiency, reduced the polishing cost, and obtained polished surface quality preferably.
Description of drawings
Fig. 1 is a diamond polishing schematic diagram;
1 is heating plate among the figure; 2 is oxidisability salt; 3 are the pressurization briquetting; 4 is diamond
Fig. 2 adopts that oxidizing substance 1 is KNO in the material removal amount comparison diagram of several different oxidizing substance polishing diamond films
3, oxidizing substance 2 is KNO
3, oxidizing substance 3 is KNO
3+ NaOH, oxidizing substance 4 is KNO
3+ LiNO
3
The specific embodiment
Further specify the present invention below by some representational example, but do not limit the scope of the invention.
Embodiment 1:
Diamond is the CVD diamond film, and surface roughness is at 3-8 μ m, and polishing area is 1.1cm
2Polishing dissolved salt oxidant consists of LiNO
3+ KNO
3, mol ratio (0.43-0.4): (0.57-0.60), 130 ℃ of fusing points.Pressure 0.2MPa, polishing disk rotating speed 81RPM, cast iron plate, 150 ℃ of mill temperature, surface of polished roughness Ra value reaches 0.4m.
Embodiment 2:
Diamond is the CVD diamond film, and surface roughness is at 3-8 μ m, and polishing area is 1.1cm
2Polishing dissolved salt oxidant consists of LiNO
3+ KNO
3, mol ratio (0.43-0.4): (0.57-0.60), 130 ℃ of fusing points; LiNO
3+ KNO
3, aluminium dish, 150 ℃ of mill temperature.
As shown in Figure 2, NaOH, KNO have been used in contrast
3, NaOH+KNO
3Three kinds of materials are done the comparison of the material removing rate of oxidant (320 ℃ of temperature) polishing diamond film.From these four kinds of methods, under lower temperature, use technology of the present invention and dissolved salt oxidant LiNO
3+ KNO
3The removal amount maximum.
Embodiment 3:
Diamond is a natural uni-crystal diamond, and surface roughness is 0.2; Polishing dissolved salt oxidant consists of LiCL+LiNO
3+ NaNO
3, mol ratio 0.05: 0.80: 0.15,174 ℃ of fusing points.Pressure 0.3MPa, rotating speed 150RPM, cast iron plate, the Ra value reaches 0.02m.