(2) Plating coat layer and effects of baking

The effects of baking have close relationship with hydrogen permeability of the plating coat layer. Plating coat layers, since being metallic, have a variety of crystalline structure. And this structure is related to hydrogen permeability. Zinc and cadmium are of hexagonal close-packed crystalline structure and of low hydrogen permeability. It is considered, therefore, that dehydrogenation is difficult by baking. For this reason, porous cadmium plating is used for aircraft parts where hydrogen is purged through the pores and cracks. Chrome plating has chrome-specific cracks in the layer that the hydrogen can dissipate, and the baking process is known to be effective for that reason.

In order for the baking process to be effective...

	1.	plating types with pin-holes,
	2.	plating types with cracks and holes,
	3.	plating types with rough coat layers,
	4.	semi-gloss and non-gloss plating

seem to be in use.

(3) Plating layer thickness and effects of baking

When purging the hydrogen from base metal and plating layers, thick plating layer will naturally be less permeable for the hydrogen. Longer baking time will be required for these cases.

(4) Process temperature and effects of baking

The baking process temperature is typically at 190~220 deg.C, but the high temperature may not be suitable for some material that loses hardness or strength by heating. In these cases, the baking time is extended.

(5) Sit-out time after plating

There are platers who set prescribed time between plating and baking such as within 30 minutes, within 2 hours, etc. for example. According to experiments with sit-out times of 1~24 hours, there seems to be little difference for the effects of baking.