1 preface
As the rapid development of science and technology, limits of aluminium alloy application expands increasingly, already was applied in appearance of plane, car, autocycle, instrument and film machinist widely at present on course of study. Aluminium alloy has good strength and tigidity not only, and the die-casting of spare parts of intricate geometry appearance can shape, came true not to have cutting treatment, craft is simple, manufacturing efficiency is tall. We use aluminium alloy to press cast first plating brightness nickel, again plating of black of a gun eletroplate craft, already managing cost, can obtain film of surface of sex of a kind of tall adornment to have distinguishing feature more again, raise a product to compete on the international market ability. Aluminium alloy eletroplates to have certain distinction with craft of general electrify plating, because aluminium alloy is a kind of more lively metal, capability of reductive, displacement is strong, to eletroplate craft brings many difficulty, use dip zinc method to come commonly pretreatment. The last few years, scientists and Technologists of plating of domestic dispatches from foreign news agency developed a lot of aluminium alloy to eletroplate new technology, on this foundation, we developed new-style aluminium alloy to express pre-treatment fluid -- , fluid of F of · of H · S, aluminium alloy eletroplates craft is more simple, film adhesion rises greatly, make sure aluminium alloy presses black of cast plating gun to eletroplate thereby quality.
2 aluminium alloy press cast pre-treatment
Aluminium alloy presses cast to contain silicon taller, the surface often has persnickety aperture and aperture presence, to achieve outward appearance of tall adornment sex, need mechanical polish. Because the hardness of aluminium alloy is inferior, mechanical rag wheel wants softness and have certain flexibility, lest horn of edge of the spare parts when mechanical polish is out of shape. Pre-treatment basically has organic dissolvent defatted, alkaline corrode, acid etching, the processing such as fluid of F of · of S of dip H · .
2.1 organic dissolvent are defatted
Use the organic dissolvent such as benzine, 3 chloric ethylene commonly defatted, in order to dissolve mineral cream with polishing, solution of usable also scour is swabbed.
2.2 alkaline corrode
For surface of eliminate spare parts slight grease is mixed 2 O of A ｌ 3 film, undertake cankerous in weak base fluid, produce microcosmic surface roughness in order to expose aluminium alloy matrix. Dan Rong fluid is alkalescent and unfavorable too strong, want to dominate the temperature of alkaline corrode fluid and alkaline corrode time strictly at the same time, lest had produced cankerous phenomenon, condition of alkaline corrode craft is as follows:
2 CO of N ａ 30 ｇ of of of of of of of 3 / L