MICRO-CRACK AND DOUBLE-COATING

The deposition structure of conventional hard chrome plating depends on the procedure, with the configuration being more or less hexagonal.

Chromium hydrides form in the crystal structure due to co-deposition of hydrogen. These unstable compounds subsequently decompose, which leads to deformation of the original crystal structure and the generation of internal stresses that generate typical cracked structures.

An average of 5 cracks/mm appear during conventional hard chrome plating. (photos A and A.1).

Tecnocrom Ind. S.A. has access to the very latest breakthroughs in hard chrome plating baths, which have similar characteristics to their conventional counterparts but a different structure is formed upon deposition. These baths include "micro-crack hard chrome plating", which considerably increases the number of cracks, thereby reducing their depth (an approximately 10-fold increase with respect to conventional chrome plating; see photos B and B.1).

a b
a1 b1

Micro-crack hard chrome plating improves various aspects. Firstly, it increases the "corrosion resistance", as the larger number of cracks and their lower depth prevents corrosive elements penetrating to the substrate, and secondly it improves the "wettability", thereby allowing oil films to be applied more easily and improving the friction gliding properties.

Another of the breakthroughs achieved by Tecnocrom Ind. S.A. in the field of hard metal coatings involves the combination of a layer of "electroless nickel" with a layer of "hard chrome", thus combining the best characteristics of these coatings to achieve "corrosion resistance and surface hardness". (photo C).

c

 9001        9100        IAQG