Iron and steel is made chemical polish

5 2. The influence test piece that phosphoric acid chroma corrodes weightlessness and reflection rate to test piece uses mild steel (C<0.

3% ) piece make. Of test piece corrode weightlessness to be decided by the weight difference of polishing around test piece. The brightness consumed reflectivity of test piece surface expresses. Serve as for the lens face of 100% with reflection rate fiducial, UV-240 of the ferry that use an island ultraviolet - visible spectrophotometer checks, wavelengh limits 600nm~800nm. Graph 9-1 is H2SO4 32% , HNO3 8% , h2O 8% , t=100 ℃ , phosphoric acid chroma determines when T=2min by 40% change to 65% when the corrodes weightlessness and reflection rate change circumstance of test piece. See by graph 9-1, phosphoric acid is one of main body part that form film of liquid state mucus in chemical polish, it raised the viscosity of polishing fluid not only, mainer is it can be in with the iron ion that corrodes dissolve unship to come by the metal of polishing apparently the much nucleus that forms stickiness (namely many iron are ionic) distribute system more (it is phosphoric acid here) cooperate content film, namely the sticky lilquid film that common weighs. This mucus film can be mixed as metallic matrix between solution noumenon diffuse obstacle layer, it is in metallic surface is raised part is small, the metal is ionic by metallic surface raised place passes diffusion layer Xiang Rong fluid is noumenal diffuse rate is rapid, and metallic surface caves film of place criterion mucus is deep, the metal diffuses ionicly rate is slow, make raised place preferential and deliquescent, undertake achievinged full smooth effect of the surface repeatedly so. Phosphoric acid density is too low, polishing fluid viscosity is low, form mucus film not easily, the surface makes the difference that make the same score a gender, polishing effect is poor; Phosphoric acid chroma is exorbitant, criterion polishing fluid viscosity is too big, polishing rate is slow, although can achieve full smooth result, but the surface is lacklustre, affect brightness likewise. By the graph 9-l still can be seen, phosphoric acid chroma is when 50%~54% polishing effect is best. Increase as pH indicator of the phosphoric acid in polishing fluid additionally, solution viscosity greatens, slow down metallic ion faces solution by metallic table noumenal diffuse, bring about the weightlessness drop off of iron thereby. Nextpage 3. The influence graph 9-2 that nitric acid and vitriolic chroma corrode weightlessness and reflection rate to test piece and graph 9-3 are test piece respectively corrode weightlessness and reflectivity to follow nitric acid and curve of change of vitriolic pH indicator. See by the curve of weightlessness of corrosion of metals of two graphs, increase as pH indicator of the nitric acid in polishing fluid, iron piece deliquescent quantity increases gradually, but increscent scope is reduced gradually. This makes clear, nitric acid basically removes oxidation in polishing, it decided film of metallic surface oxidation generate, along with nitric acid pH indicator of film of elevatory, oxidation generate rate to accelerate, the weightlessness that creates a metal is reduced relatively. Additional, increase along with vitriolic pH indicator, weightlessness quantity of the metal increases gradually, and increase extent is strengthened gradually, this end at vitriolic the deliquescent action to oxidation film. By the reflectivity curve in the graph, we see not hard, the brightness of low nitric acid density and test piece of tall iron and steel of vitriolic chroma correspondence is taller, because high vitriolic concentration and low nitric acid density ensured the deliquescent rate of oxidation film is more than his to make rate,this is, achieve shining effect thereby. But, if nitric acid density is too low, form oxidation film not easily, effect of short of brightness. Vitriolic chroma is exorbitant, the deliquescent rate of oxidation film is too rapid, what will bring about metallic matrix is inhomogenous deliquescent, make the brightness of metallic surface drops. 4. The chroma of the water in polishing fluid is right iron piece the weightlessness that corrodes weightlessness and the influence test piece that reflection leads and the metabolic curve that reflection leads content of the water in following polishing fluid are shown at graph 9-4. See by graph 9-4, to achieve best polishing result, the content of the water in polishing fluid should be controlled as far as possible in low chroma limits, if 7%~9% is controlled. Continue to lift as the content of the water in polishing fluid, mucus layer is destroyed, metallic ion is in metallic surface is raised be in and cave of place diffuse rate difference is reduced, bring about whole smooth sex to become poor, brightness drops. 5. Polishing fluid temperature and polishing time are right iron piece the corrodes weightlessness and reflectivity to let polishing fluid temperature and polishing time change curve that the influence graph 9-5 that corrodes weightlessness and reflectivity and graph 9-6 are steely test piece respectively. See by graph 9-5, the rate that the metabolic curve that the weightlessness of steely test piece follows temperature is a model - temperature curve, namely as temperature elevatory, deliquescent rate of the metal increases gradually. Temperature is too low, deliquescent quantity of the metal is little, density of ion of the metal in polishing fluid is low, the viscosity of polishing fluid is low also, form stickiness lilquid film not easily, polishing effect is accordingly poor; Temperature is too high, the viscosity of polishing fluid drops, easy create metallic appearance corrode too, brightness drops quickly. Accordingly, polishing fluid temperature should be controlled between ℃ of 100 ℃ ~110. See by graph 9-6, in the begining, as the extension of polishing time, of the metal corrode weightlessness quantity to greaten quickly. When 1min~2min, weightlessness curve gradually hasten is smooth, and corresponding iron piece have the biggest brightness. As a result of,this is right now polishing rate by diffusion control, achieved namely diffuse evenly. Continue to lengthen when polishing time, metallic weightlessness is accelerated quickly again, metallic surface has appeared to corrode, brightness drops. So general polish 1min~2min can. Nextpage3, low, medium carbon steel is in oxalic acid - the chemical polish in crossing oxidation nitrogen solution 1. Low, medium carbon steel makes the composition of polishing fluid and craft requirement oxalic acid - the composition that crosses fluid of polish of chemistry of oxidation hydrogen system and craft condition collect rank to express 9-2 in. By the watch 9-2 is seen, the chemical polish fluid of this one type is to had used oxidation hydrogen to replace nitric acid to use oxidizer as polishing, it won't produce harmful azotic oxide, generate beneficial oxygen however, because this is craft of polish of a kind of hurtless. What accept put oneself in another's position as iron ion basically is oxalic acid or fluoride (hydrofluoric acid or fluorine change hydrogenous ammonium) , benzoic acid and urea are the corrosion inhibiter of iron, can be passed in order to prevent the iron when polishing to corrode. Because cross oxidation hydrogen and oxalic acid to suffer pyrolysis easily, accordingly the use temperature of fluid of this kind of polish is controlled mostly it is under 30 ℃ , also join sometimes a few cross oxidation hydrogen stabilizing agent to come to those who had reduced oxidation hydrogen decompose. To maintain the polishing effect of chemical polish fluid, cross oxidation hydrogen and oxalic acid to should be pressed a few for many times means has complement, fill every time commonly had added oxidation hydrogen 5mL/L~10mL/L, fill add oxalic acid for 2.

5g/L~5.

0g/L is advisable. Carry out a proof, recipe 3 use at common iron wire (φ 1.

0) the effect of exterior polish is very good, but 1:1 should be used before polishingDip washs hydrochloric acid aqueous solution activation. Recipe after 2 polish make an exterior darkly gray, and easy occurrence stripe, should join right amount surface activator right now. Recipe 5 it is the spare parts on machine of spin spun yarn - Luo La - craft of special and chemical polish. With the recipe 7, when 8 polish, answer to often examine the PH cost of polishing fluid. When PH is exorbitant, usable hydrofluoric acid is moved low, fill every time hydrogenation fluorine is acerbity with 4g/L~6g/L advisable. When the iron in polishing fluid when content is higher, PH value can be reduced 1.

7~2.

1. Recipe 9 have solution service life long, waste liquid but second birth is used circularly wait for a characteristic. When making up solution, use place vitriolic dilute first and place alone, take the water of 1/2 dosage additionally, change fluorine hydrogenous ammonium slowly join agitate again deliquescent, ordinal had joined activator of oxidation hydrogen, urea, attenuant already vitriolic, surface. Should dissolve completely even hind, reoccupy water dilute comes formulary bulk. The defect of this craft is brightness very not tall, other part is added again after wanting to divide iron ion when retexture. The polishing effect of 8 can raise the recipe along with the rise of temperature. When temperature amounts to ℃ of 95 ℃ ~96% , need several seconds to be able to achieve clear polishing result only. 2. Polishing fluid composition and craft condition are right oxalic acid - the influence Hickling geometric ratio that crosses effect of polish of fluid of oxidation hydrogen polish studied iron and steel is in in some detail oxalic acid - all sorts of phenomena when the polish in crossing oxidation hydrogen fluid. He points out iron to be able to form an oxide film when polishing, this kind of oxide film will be deliquescent by corrode of oxalic acid dip. It is at the same time in the chemical polish process of steel, have oxygen and carbon dioxide gas at the same time separate out, and its bulk is roughly equal. Oxygen is the product that passes oxidation oxyhydrogen action, and carbon dioxide gas is the child that oxalic acid returns primary effect. Hickling has thought to oxidize to hydrogen makes iron oxidizes and form tervalent ferric oxide (Fe2O3) film, this kind of film but by oxalic acid reductive into diatomic iron, and by dissolve in acidity solution. In the loop that because this is steely,the surface produces partial passive state at active state ceaselessly. The cycle of aeriform separate out is accompanying the metabolic cycle of the potential that answers relatively. Graph 9-7 is steel in 0.

The potential of the steel in the oxalic acid solution of 3mol has followed the concern that oxidation hydrogen content changes. Electrolyte composition: Cross oxidation hydrogen, h2O2 (30%) 139 oxalic acid, h2C2O4.

2H2O 25g is vitriolic, h2SO4 0.

1g water, h2O 1L the following temperature agitate of 30min~60min of 20 ℃ time cannot agitate is seen by graph 9-7, in the major while of one cycle, the potential of steel is approximated + O.

5V, it is rapid after a cycle is over turn into 0, restore original numerical value again after that. When the density that crosses oxidation hydrogen is low, of occurrence iron slight dissolve and separate out a few gas, the surface is lacklustre or cover a film. When [the ratio of H2O2]/[H2C2O4] is approximated 1 when, the potential of steel turns into (9-7 seeing a picture) , be in potential 0.

Inside 5v limits, potential begins periodic change, be equal to to the chroma of H2O2 all the time 1.

When Lmol till (the area of the hatching that draw shade) . The characteristic of polishing process is the periodic commutation of the activation of steel and partial passivation process. The content prep above when H2O2 1.

When 1mol, steel turns into completely passive state, and dissolve no longer actually. Become consequently [the ratio of H2O2]/[H2C2O4] is equal to 1 or when be more than L (in 3 the following) , ability polish mild steel. The periodic change of this kind of potential also is in aluminous acidity chemistry observes in polishing fluid. Iron lies in whole cycle deliquescent condition (9-8 seeing a picture) , but fall solution is the most acuteness is in potential the most negative when. In potential most when, film of oxidation of a passivation is covered on iron. What the deliquescent speed of steel follows oxalic acid content is elevatory, the rise of electrolyte temperature, and the degree with acuteness agitate and increase. Electrolyte is OK also a bit thicker (to oxalic acid complete saturation) , however the scale of each composition should be in afore-mentioned limits. In thicker electrolyte, as a result of the convection of electrolyte, can have on polishing test piece " stripe " shape organizes generation. Below afore-mentioned optimal polish conditions, the deliquescent speed of steel is equal to 10.

2 μ M/h (9-8 seeing a picture) . After passing 50min polish, exterior surface roughness by 0.

Bring down of 99 μ M arrives 0.

66 μ M, and after polishing 90min, criterion the bring down arrives 0.

53 μ M; If former surface roughness is 0.

48 μ M, so after polishing 50min and 90min, exterior surface roughness can fall 0.

33 μ M and 0.

30 μ M. Nextpage mild steel (C ≤ 0.

3% ) in oxalic acid - the polishing effect in crossing oxidation hydrogen fluid is better. When if be contained in steel,making an appointment with the carbon of 1% , its surface is easy after polishing appear deep depression stain, make of the surface glance the gender becomes poor. To low-alloy steel, what its have alloy composition to comprise apparently in chemical polish process is residual generate, its characteristic is cycle of aeriform separate out lower, form surface of composition Xiang Gang each because of electrolyte it is more as a result of residual existence difficult to diffuse. The hydrofluoric acid that should add quality in polishing fluid right now or fluorine change hydrogenous ammonium, the polishing result that can improve medium carbon steel apparently (9-2 seeing a table) . The complexing that joins iron (match) agent or corrosion inhibiter (if 2 phenol, double pyridine mixes benzene pyridine) the separate out process of gas of meeting slow down, improve polishing result. Join corrode accelerant (like chloride etc halide) can reduce polishing effect greatly. Join a few surface activator, especially all sorts of blame ion with couple surface activator, often can improve polishing result, at the same time its bubble can restrain the generation of the gas in polishing process, had improved the service life of oxidation hydrogen or polishing fluid. Oxalic acid - the steely surface after crossing polish of oxidation hydrogen fluid is oxidized not easily to corrode in air, have good adhesion to the plating nickel layer of small city at the same time, because this is comfortable the polish at the base material surface as plating thick nickel. If be in oxalic acid - hydrofluoric acid is added in passing oxidation hydrogen system, fluid of this kind of polish can use Yu Hangui (Si ＜ 2.

8% ) the chemical polish of ferroalloy. Because cross oxidation hydrogen easy decompose, just had made up so change cast solution reaction is very severe, later wear off. Should make full use of chemical polish fluid, managing cost, had better be make those who need chemical polish a concentration undertake handling, polishing fluid deserves to be used now now. When be like the reoccupy after polishing fluid sets period of time, need complement crosses oxidation hydrogen and oxalic acid. When solution abate already to cannot again when polishing, should change entirely polishing solution. Additional, the reaction of chemical polish is exothermic reaction, can make solution temperature elevatory, quicken those who cross oxidation hydrogen to decompose. Because fluid of the polish when this polish needs to cool, had better have charge lukewarm unit. To pulverous metallurgy (be squelched by iron pink and become) , layer of oxidation of black of easy generation of the surface after chemical polish. Should be after chemical polish in hydrochloric acid solution ability can show full burnish. 4, high-carbon steel is made chemical polish 1. The condensation phosphoric acid quantity that contain carbon is in 0.

6%~2.

The high-carbon steel of 0% (wait like T10, 20AP) make, after the course quenchs or quenching mostly temper processing, its chemical polish is relatively accordingly difficult. The chemical polish fluid that can feed use high-carbon steel at present basically has two kinds big. The first kind is condensation phosphoric acid model. Condensation phosphoric acid is make work by city phosphoric acid (75%~89%H3PO4) get via drying of 150 ℃ above. Also can join 2 phosphor of 5 oxidation with phosphoric acid of city carry out (P2O5) get at dissolving near 100 ℃ . Basis of condensation phosphoric acid differ and form of condensation polymerization temperature 2 get together, 3 get together, 4 get together, 5 get together, 6 get together... get together more phosphoric acid, its characteristic is as won't ionic as the iron in aqueous solution generation not the phosphoric acid iron of dissolve sex precipitates. Accordingly, polishing effect excel is common phosphoric acid. Watch 9-3 listed the composition of fluid of condensation phosphoric acid chemical polish and craft condition. Recipe 1 divide comfortable at high-carbon steel outside, the polishing face of pear face shape can be gained when be being used at stainless steel of chromium steel, chromic nickel, should join chloridize right now inferior antimony of stannum, chloridize, vitriolic aluminium all but. Additional, a few chromic acid are added in condensation phosphoric acid (CrO3) , effect of ameliorable also polish. 2. Cross oxidation hydrogen - the juice of the 2nd kind of chemical polish that fluorine turns azotic ammonium high-carbon steel is to cross oxidation hydrogen - fluorine changes hydrogenous ammonium model. Express what 9-4 listed high-carbon steel is used to cross oxidation hydrogen - the composition that fluorine changes fluid of hydrogenous ammonium polish and craft condition. When making up polishing solution, two kinds of solution should make up armour, second respectively, deposit alone. Had better be make up before use. The action of wetting agent is joined in armour fluid, it is the brightness that the help improves chemical polish appearance. The bleeding agent that appropriate chooses mew scour or imports the exterior activator such as Tejituoer. After polishing solution has matched, ought to use vitriolic or phosphoric acid adjusts PH=2~3, had made oxidation hydrogen is in compare steady state. Before polishing exercise undertakes, can press (bulk compares) the following scale: Armour fluid: ? Second?10:1Undertake mixture, can use after mix is even. Before chemical polish, need to undertake be cleaninged thoroughly to making an appearance, divide smeary hind, reoccupy activation of pickling of aqueous solution of 10% hydrochloric acid, rinse clean with cold water. Of exterior existence burr make, undertake burr is handled going even. When polishing, because polishing reaction is exothermic reaction, the temperature appropriate that reason wants to control polishing solution is low should not be tall. After polishing, want to use tap water of going from place to place quickly to be rinsed adequately clean, the alcohol dehydrate with clean reoccupy is dry. Carry out a proof, influence high-carbon steel makes the crucial factor of a chemical polish effect, not be the absolutely content of some kind of constituent in solution, however of the content of a few kinds of main constituent than. More appropriate scale is: Does fluorine change hydrogenous ammonium: ? =3g/L:3 of oxalic acid of? of  wholesale 0mL/L:1G/L 3. Note (1) in successional batch polish exercise, want to achieve stabler polishing result, must be decomposed easily to be heated or the solution constituent with big wastage undertakes complement and be adjustmented in time. When to fill add, how long fills, fill every time how many, all want by particular case (if cast finishing how many, the composition of polishing solution) control of take into consideration the circumstances. The most intuitionistic basis is the brightness change circumstance of polishing surface, be adjusted namely according to polishing effect. Except in front a few kinds of constituent of the introduction fill outside increasing an amount, fluorine changes hydrogenous ammonium (with hydrofluoric acid form) fill increase an amount with every time 4g/L~6g/L is advisable. (2) the city cost of chemical polish solution should be stabilized commonly in 1.

5~2.

5 between. (3) in chemical polish exercise, the iron content in polishing solution shows those who accumulate a gender to increase. When iron content is exorbitant, polishing quality and work efficiency all can be reduced accordingly. Document points out, fill after adding constituent of a few easy loss, when the polishing effect that is like solution still cannot be improved apparently, the iron content that can think this solution is medium is exorbitant. Should abandon at this moment old change new. Compare mature experience, the content that is the iron in polishing solution does not get prep above 35g/L. (4) because cross rare chemical polish solution, had caused easily in polishing process to polishing surface corrode a phenomenon, reason should avoid to had used rare solution as far as possible. The attenuant effect that to avoid polishing exercise causes to polishing solution, but will wait for polishing to make an advanced travel dry heat with close of polishing solution temperature hind, again person chamfer polish. When encountering too rare solution, should try to adjust add thick. (5) low temperature of appropriate of chemical polish exercise (℃ of 15 ℃ ~25) operation. Polishing chamfer appropriate is deployed drop in temperature equipment. CNC Milling CNC Machining