Posted by Gordon England (62.252.0.12) on 11:07:42 31/05/06
In Reply to: Re: contamination in TBC bond coat posted by Leon
Hi
1. Ventilation air flow can play an important role in coating
quality in some circumstances. You will notice this particularly
when spraying into internal spaces where good ventilation is
difficult to achieve. Over-spray material and dust are not removed,
then get entrained back into the spray stream and get included in
the coating.
2. For any given powder (as mentioned by Leon powder chemistry,
size etc. will produce different effects) the colour of the
coating will be effected by the coating temperature during
application. Generally, a grey/white colour indicates coating is
too cool and a yellow/orange colour too hot. You should not use
that as a rule of thumb for coating quality, but noting colour
changes can be useful during coating development and monitoring
coating quality as this reflects changes in spraying
parameters.
Regards Gordon
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