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Report is silver-gilt craft is improved mediumly in beryllium bronze spare parts
From;    Author:Stand originally
<P><FONT&nbspface=Verdana>[summary] the characteristic proceed with from material of analytic Beryllium bronze, specific aim ground takes significant pre-treatment craft step, take the place of with sulfur sulfate is silver-gilt the poisonous cyaniding that replaces a tradition is silver-gilt, the reason that analysed silver-colored film to become angry put forward to be fought accordingly become angry processing measure. &nbsp</FONT></P>
<P><FONT&nbspface=Verdana> &nbsp[keyword] without cyanogen silver-gilt; Beryllium bronze; Passivation; Pre-treatment; Fight become angry <BR> The graph in &nbsp[classifies date] TQ153.1   [document label is piled up] B   [article number] 1001-1560(2006)02-0065-02<BR> &nbsp0 introductive <BR> &nbsp Beryllium bronze is the special green copper alloy that contains 0.5% nickel of 2.5% Beryllium of 1.7% ~ , 0.2% ~ . Classics of beryllium bronze material quenchs very high mechanical intensity, wearability, stretch fatigue intensity and hear resistance are had after ageing treatment, still have conduct heat, electric, wait for function without magnetism, especially temperature change is stretch to its the impact is very little. Accordingly, this material is used at making the stretch spare parts of high metamorphic load wait mostly, be applied extensively at the industrial branch such as electric equipment, aviation, spaceflight. To improve performance of its electric conduction, be in commonly Fu of its surface plating film of Beryllium of sex of a function, ply is 5 ~ normally 8 μ M. Traditional report is silver-gilt use technology of virulent cyaniding plating, environmental pollution is serious, endanger human body health. In addition, silver-colored film of surface of beryllium bronze spare parts often is united in wedlock undesirable, still have silver-colored film the problem such as changeful color. Accordingly, report of beryllium bronze spare parts is silver-gilt must give integrated consideration. <BR> Character of material of &nbsp1 Beryllium bronze and silver-colored film become angry case study <BR> The Beryllium that easy passivation contains in composition of alloy of &nbsp Beryllium bronze, nickel and titanium, although be in normal temperature air, the surface also can make the compact oxidation film with an invisible naked eye very quickly. In the meantime, beryllium bronze spare parts often should pass anneal, quench the heat treatment working procedure such as effectiveness for a given period of time, even if use vacuum heat treatment, the surface also produces the oxidation of different level inevitably. The composition of film of oxidation of surface of beryllium bronze material basically has CuO, Cu2O, BeO, NiO, Ni2O3, TiO2 to wait, oxidation film is compact and thick. Oily ungodliness is divided before heat treatment sometimes, skin of oily dirty, carbon black, oxidation can be generated to wait in spare parts surface, pre-treatment giving plating increased difficulty. Before eletroplating, do not keep clear of these clean thoroughly, make sure spare parts surface is purified, activation, can create silver-colored film and base tie undesirable, appear bubbly, desquamate, flake wait for breakdown, use special pre-treatment process only, ability assures the quality of silver-colored film effectively. <BR> Although &nbsp silver-colored film is chemical stability is taller, but be in especially in atmosphere contain industry in the air that harmful gas is like H2S, SO2, Cl2, CO2, NOx to wait perishable corrode becomes angry, from silvery white, flaxen, Brown wait for gradual change to black. Below high temperature condition, this kind is corroded become angry the phenomenon is more acuteness. Undoubted, the sulfide in air if H2S, SO2 and silver-colored surface contact form Ag2S is to cause the main reason that become angry, in report in silver-gilt operation, plating clean sordid, the be mingled with in film has metallic impurity, organic thing, coarse, hole leads film advanced metropolis forms small cell to corrode, make silver-colored film becomes angry quickly. Silver-colored film becomes angry affect film exterior not only, still can reduce weldability of electric function, deterioration to wait. So, to report silver spare parts adopts plating to be fought effectively become angry processing is to make sure place of silver-colored film quality is indispensable. <BR> Report of spare parts of &nbsp2 Beryllium bronze is silver-gilt craft <BR> &nbsp2.1 pre-treatment <BR> &nbsp can undertake by groovy method organic dissolvent divides oily, alkaline degreasing or electrochemistry to remove oil, yi Ke removes oil with cleaning an agent with the metal, make sure surface of complete purify spare parts is smeary. When successive and complete water film is shown in spare parts water intrusion, make clear smeary already kept clear of clean thoroughly. <BR> &nbsp can choose method of the following either to corrode activation surface according to state of spare parts surface. <BR> Thicker to exterior oxidation film or &nbsp(1) is adherent oily dirty, carbon black the beryllium bronze spare parts that wait, can be its in the alkalescent solution that contains 150g/LNaNO2 of 400 ~ 500g/LNaOH, 100 ~ immerse below 100 ℃ 15 ~ 25min, in order to shake oxidation film layer, reheat water is cleaned clean, water of going from place to place is rinsed adequately, corrode of the dip in the mixture solution that containing 150g/LH2SO4 of 300 ~ 500g/LHCl, 100 ~ and Niao of 0.5 ~ 1.0g/L sulfur next 1 ~ 2min, with film of oxidation of complete eliminate surface, reoccupy flow water is cleaned adequately. After spare parts surface shows even brightness, can undertake electrodeposit. <BR> The beryllium bronze part with smaller to film of oxidation of spare parts surface &nbsp(2) , be in via eliminating oily eliminate appearance adequately smeary, after purifying the surface, macerate can undertake in following solution, with activation surface:   of <BR> <BR>   (after the spare parts classics with thinner to film of oxidation of spare parts surface or relatively accurate 3) purifies the surface except oil, in the following solution macerate activation has better activation effect: Classics of <BR> <BR>   the beryllium bronze spare parts of afore-mentioned methodological activation, light can give in HNO3(d=1.42g/cm3) solution 1 ~ 5s, after water of going from place to place is rinsed clean, can undertake eletroplating silver-colored. <BR> Report of spare parts of &nbsp2.2 Beryllium bronze is silver-gilt <BR> &nbsp is the adhesion that ensures silver-colored film of beryllium bronze spare parts and matrix are good, in choose before the report that do not have cyanogen is silver-gilt, should preexistence undertakes dip silver handles in the following solution: <BR> <BR> &nbsp chooses not to have cyanogen or low cyanogen matchs an agent to replace virulent prussiate, with sulfur acting sulfate silver-gilt solution adds appropriate brightening agent and exterior activator to regard report as silver-gilt plating fluid. Namely: <BR> <BR> &nbsp shining additive takes the place of with sulfur compound of the amino Niao, compound that contain sulfur, the heterocycle that contain nitrogen and activator of blame ion surface get together it is certain that glycol is pressed scale answer deserves to join can, carry out of city of optional also choose does not have cyanogen silver-gilt and shining additive. <BR> Cathode is used to move to have better effect to assuring silver film quality when &nbsp is conditional. In report in silver-gilt process, want to adjust the distance between positive pole of nice private parts and position appropriately, the attention controls shade, zincous area ratio to be in 1: 1 ~ inside the limits of 2, notice the PH that control and adjusts silver-gilt electrolyte regularly is worth, each bases content adjusts electrolyte of period analysis assay in time compensatory, maintain electrolyte stability. It is affirmatory and advisable that the complement of shining additive experiments through suddenly Er chamfer, can use add the method that adds frequently less, be helpful for assuring silver-gilt quality. If can use pulse power source to undertake pulse eletroplates conditionally, quality of silver-colored to rising film and fight become angry ability has more apparent effect. <BR> Of silver-colored film of spare parts of &nbsp2.3 Beryllium bronze fight become angry processing <BR> &nbsp suffers the harmful gas such as sulfide, halide to corrode in atmosphere to prevent silver-colored film become angry, make film exterior and electric conduction, solder etc function is insusceptible, should use to silver-colored film normally fight become angry processing. Commonly used method has chemical passivation, electroanalysis passivation, dip organic diaphragm. <BR> &nbsp2.3.1 chemical passivation handles <BR> Passivation of &nbsp ① chromate handles craft to be as follows: <BR> &nbspK2Cr2O710 ~ 15g/L, HNO3(d=1.42g/cm3)10 ~ 15g/L, temperature chamber is lukewarm, passivation time 10 ~ 30s. <BR> Parallel of &nbsp ② benzene craft of passivation of 3 nitrogen Zun is as follows: <BR> &nbsp benzene parallel 2 ~ of 3 nitrogen Zun 4g/L, sulphur radical is salicylic 2 ~ 5g/L, 12 alkyl are vitriolic sodium 0.2 ~ 0.5g/L, PH is worth 2 ~ 3, temperature is room temperature, passivation time 2 ~ 5min. <BR> &nbsp2.3.2 cathode electroanalysises passivation craft <BR> &nbspK2Cr2O725 ~ 30g/L, al(OH)30.5g/L, PH is worth 6 ~ 8, temperature is room temperature, jc=0.1 of cathode current density ~ 0.3A/dm2, positive pole is stainless steel board, time 3 ~ 5min. <BR> &nbsp appropriate uses Al2(SO4)3 and NH4OH to react adequately, generate fresh Al(OH)3 precipitation, the course obtains Al(OH)3 after filter eliminate SO42- , in joining its passivation electrolyte again. <BR>2.3.3 dip besmears organic prevent silver to become angry agent <BR> &nbsp home prevents silver commonly usedly to become angry the agent has water-solubility to type waits like TX, SN, organic corrosion inhibiter be like organic dissolve the form of a drug, application is more BY2, DPB 823 waits, its can form diaphragm of solid state layer in silver-colored film surface, have fight goodly become angry the effect. Using gas, when the organic matter such as Ding Chun makes the solvent of protective agent, must notice safety adequately, prevent the happening of the accident such as fire. Prevent silver to become angry one of vital technology measure that dip besmears protection is to raise silver-colored film to fight corrode function, want serious operation, note dip besmear quality, achieve effectively prevent the end that silver becomes angry and assures silver-colored film quality. <BR> &nbsp3 film quality detects quality of silver-colored film exterior passes sight control, requirement film is crystal and meticulous, successive and complete, union is good, bright and clean, show the silvery white with even colour and lustre, without coarse, hair dark a skin, bubbly, fall off, hemp dot, scorch disease waiting for defect, the exterior is unqualified person should grant eliminate and repair weighs plating. Silver-colored film ply should satisfy engineering technology requirement, be in commonly eletroplate sample randomly in the process, measure generous standard to determine with a bit law or nondestructive film ply eletroplates with deciding time. The adhesion of film and matrix is executed nonsked selective examination, use fatigue bend test legal sex determines, be about to plating reverse bending comes, observe with magnifier whether film removes skin, chap, show without this phenomenon adhesion is good. Fighting discolouration can be to be in below room temperature in aqueous solution of 0.1mol/LK2SO4 of immerge of will silver-gilt test piece normally, immerse the metabolic case that blot appearance moisture content takes out to watch film after 30min, the time of occurrence change grows more, show silver-colored film is fought become angry ability is better. </FONT></P>
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