All chromium is about the same hardness; 800 to 1000 VHN - very hard! The main difference lies in the thickness of the deposit of chrome coated on the metal.
For decorative purposes, chrome sits best on nickel which itself adheres very well to copper - this combination also offers the best corrosion protection resistance more better. Decorative chrome coating thickness will vary from a few hundredths of a mil to 1 mil. The mirror finish will only be as good as the finish you put on the surface before you put on the chrome.
For functional purposes, to take advantage of the extremely low chrome coefficient of friction, or for wear build-up (bearing surfaces or pistons, as examples), hard chrome is plated in thickness as required from 1 to 50 mills.
When used as a bearing surface. Chrome must be micro-finished (more on this later) and will then provide a coefficient of friction lower than any other metal when used against steel, iron, brass, bronze, babbitt, or aluminium alloys. Do not use chrome against chrome. Because chrome is also much harder than casehardened steel, we then have a perfect set-up for longwearing working surfaces. Chrome will resist mostly all organic and in organic compounds and acids, except hydrochloric acid (muriatic).
Tidak ada komentar:
Posting Komentar