Be in brassily nitric acid
- source:LENA CNC Machining
84g/cm3) , 6% thick nitric acid (density 1.
42g/cm3) , 0.
Activator of 05% OP-21 surface and 69.
95% water, at room temperature (2 ℃ of 25 ℃ ± ) next polishing 10s, 40s, with the photograph of scanning report lens when 80s. Can be clear about by graph 2-26(a) see, be in brassily in immerge polish fluid when 10s, its surface already corroded and appear a lot of corroding hole, when it and cupreous chemistry polish corrode level to answer relatively, namely the first phase of chemical polish is to erode level, continue to lengthen when polishing time, brass surface becomes shining gradually. Graph 2-26(b) is the photograph of scanning report lens when brass polish 40s, of the first phase corrode hole to already disappeared, the surface becomes very flowing and shining, the 2nd phase that already entered chemical polish right now namely -- brightness changes level. If continue to extend polishing time (if amount to 80s) , exterior brightness drops, and appear a lot of hemp dots, this can see from graph 2-26(c) , the 3rd phase that right now polishing enters chemical polish -- corrode level too, because the aeriform institute of generation stays and the surface causes a lot of hemp drops. 2, the reflection when the polish below chroma of different nitric acid leads brass - when polish of chemistry of time-speed-distance curve brass, chroma of the nitric acid in polishing fluid is led to reflection - the influence of time-speed-distance curve is shown like graph 2-27 place. By the graph 2-27 can be seen, the beginning in chemical polish level, the reflectivity of test piece surface drops quickly, right now brass surface also appears corrode hole, this is corresponding at corroding level. Study the polishing process when content of different nitric acid, discover its reflection is led - time-speed-distance curve all has similar figure, the chemical behaviour that shows polishing process is similar, when nitric acid density is low, the career that polishing begins level reflectivity to drop is slower, the time of continuance is longer (highest amount to 50s) . Lift as nitric acid pH indicator, the speed that reflectivity drops is accelerated gradually, continuance time shortens gradually, when nitric acid chroma amounts to 130mL/L, continuance time counts a second only, turn namely subsequently person brightness phase, right now reflectivity rises gradually and reach stabler highest value (even area of the curve) , when nitric acid density is low, the highest cost of reflectivity is low also (highest reflectivity is 47%) when HNO3 30mL/L, rise as nitric acid pH indicator, the highest cost of reflectivity also rises, achieve gradually 74% . But nitric acid density is too low with too tall when, the width of the even area of highest reflectivity all narrow, be in with NHO3 chroma the even area of the tall reflectivity when 60mL/L~90mL/L is the widest, have economic value most right now, the chroma that uses nitric acid on one hand is inferior, pollution is little, cost is low; Gain shining face steadily right now on the other hand, polishing time differs 30s is not had to polishing effect how old difference, this is helpful for large-scale industrialization use on production. Nitric acid chroma is exorbitant (if amount to 13OmL/L) when, although corrode the time of level very short, the time that Dan Guangliang spends level is very short also, had appeared very quickly to corrode (reflectivity drops) , because the time of stable brightness is too short, this is controlled very hard on production, because this gets consistent from beginning to end polishing result not easily. Nextpage3, brass is led in the reflection when the polish below different and vitriolic chroma - 2-28 of time-speed-distance curve graph is brass in chemistry of different and vitriolic pH indicator the reflection when the polish in polishing fluid is led - the influence of time-speed-distance curve. See by graph 2-28, reflectivity of the earning when different chroma is vitriolic - the appearance of time-speed-distance curve is the curve when be similar to nitric acid to change, they also can be divided into 3 area, what answer relatively with these 3 area is to corrode, shining, corrode 3 phase too. As heighten of vitriolic pH indicator, the time that corrodes level shortens, it is when vitriolic chroma inside the limits of 200mL/L~260mL/L, its are highest reflectivity change is very little, explain influence of vitriolic pH indicator is far the impact that compares nitric acid is little, tall pH indicator is vitriolic do not provide oxidisability, it raises the viscosity of polishing fluid only, be helpful for polishing mucus film form, accordingly, vitriolic concentration increases inside certain chroma limits, can quicken mucus film form. After the concentration that already formed mucus film more than when vitriolic chroma, continue heighten chroma does not show the result, this is the point with it and different nitric acid. 4, exterior activator OP-21 is brass to chemical polish the influence graph 2-29 of reflectivity is exterior activator Ren radical phenol gets together oxygen ethylene aether (OP-21) be in to brass nitric acid - the influence curve of brightness of chemical polish surface in vitriolic system. See by graph 2-29, OP-21 can be reduced corrode degree, as the addition of OP-21 content, the reflectivity that corrodes level rises somewhat, at the same time the highest brightness of brass surface has rise apparently, the highest reflectivity when having OP-10 is 54% , achieve 0 when OP-21 chroma.
When 5mL/L, highest reflectivity is as high as 80% , but the concentration that increases OP-21 further, reflectivity does not rise further, because chroma is amounted to,this is 0.
When 5mL/L, the OP-21 of metallic surface already reached the level of saturated adsorption. Everybody knows, exterior activator has very strong sorption apparently in the metal, it is certain to be had consequently delay cankerous action, in the meantime, because it can reduce the exterior pulling force of solution substantially, make the bleb of the generation in polishing process leaves metallic outside quickly, accordingly it can reduce a metal apparently when polishing corrode too. See by graph 2-29, increase as OP-21 pH indicator, the limits of shining area expands ceaselessly, corrode a phenomenon to get apparent inhibition too, corrode an area to narrow apparently too, and the reflectivity that nears Yu Guangliang area in the reflectivity inside this area. Accordingly, the affiliation of OP-21, improved the result of chemical polish apparently not only, also enlarged the working limits of polishing fluid, make it more comfortable at industrial application. Why is this namely in a lot of patent polish fluid the account that often should add exterior activator. The influence of temperature of job of fluid of nextpage5, polish to polishing effect pursues 2-30 is temperature of polishing fluid job the influence curve to brass polish effect or exterior reflectivity. See by graph 2-30, as temperature elevatory, whole polish process, include to corrode, brightness and corrode 3 phase to all appear ahead of schedule too, polishing time shortens, but the range of the even area of highest reflectivity is narrow (shorten by tens of seconds to more than 10 seconds) it is very difficult that this makes produce control to become. Accordingly, inferior temperature is used mostly when chemical polish, it is beautiful with 25 ℃ normally, the control between temperature tall Shi Reshi is undeserved, easy generation is corroded too. 6, the influence of zincous to brass and chemical polish polarization curve uses polishing fluid temperature the method that studies electropolishing will study polishing fluid temperature the zincous polarization curve when chemical to brass polish, earnings result is shown like graph 2-31 place. See by graph 2-31, the likeness when the appearance of polarization curve of earning positive pole and electropolishing, have namely initiative the corrodes area or shining area and electric current to rise again Guo Dun that the electric current when rises quickly turns an area. Temperature is low (15 ℃ ) when, passivation area or shining area (platform area) range is bigger (0.
0V) , high temperature (45 ℃ ) when, the potential range of shining area is narrower (1.
0V) . Working range is narrow, the reflection in this and graph 2-30 leads the conclusion of the metabolic curve gain that follows temperature to agree, this also proves the mechanism of chemical polish also can use electropolishing mechanism to explain. 7, be in brassily vitriolic - nitric acid - the mechanism of chemical polish in exterior activator system is led from afore-mentioned reflection - time-speed-distance curve, photograph of scanning report lens and electric current - the test result such as potential curve, can prove, be in brassily vitriolic - nitric acid - when polish of the chemistry in exterior activator system, polishing process can be divided into erode, brightness and corrode 3 phase too. And electric current - of potential curve determine to make clear as a result, chemical polish process and electropolishing procedure are completely similar, same existence is worn when electropolishing " even area " (or shining area or passivation area) , such, the mechanism of chemical polish also can use the theory of electropolishing to undertake demonstrative. Electropolishing theory thinks, appear when electropolishing " even area " because metallic surface forms stable passivation film be caused by,be, passivation film can be stickiness liquid film, also can be solid film or two kinds of film coexist. According to afore-mentioned analysises, we can explain brass chemical polish with passivation film theory. In dip corrode phase, zincous electric current lifts along with zincous potential and rise quickly, this shows brass surface produced fast electrochemistry to corrode right now, because metallic face is different,this is place has different electrochemistry active, make the galvanic cell that a lot of instantaneous close thereby, cause metallic surface to dissolve inhomogenously, create metallic appearance thereby corrode. Achieve when corrosion current quite tall when, after passing period of time, the metallic ion that exterior dissolve unship comes to has not enough time diffuse in noumenon fluid, gather in metallic surface to form stickiness liquid or film of solid shape passivation, what it controlled a metal is farther corrode, because passivation film is in,the ply that cereal of metallic surface peak is in differs, the passivation film that raised peak handles is thin, sunken the passivation film that the cereal below handles is deep, inside film consequently office of metallic surface summit dissolves much and quickly, gu Churong is solved little and slow, make metallic surface got be rectifyinged microcosmicly making the same score thereby, show taller brightness or reflection rate, reached the level of polishing at this moment. Lengthen of time further as polishing, passivation condition of the metal is broken, lift and rise what electric current follows potential again, metallic surface is corroded again, weightlessness increases, reflection rate falls, because right now gas arises in great quantities, be in because of gas of the surface stay, the result produces hemp drop very easily, because appearance of this this one stage can have appeared,corrode hole and hemp dot. This can be clear about from inside scanning report lens see. CNC Milling