adhesion of coatings

Posted by Alecxei Goncharov ( on 14:22:37 11/01/06

Hi, I ve read your article Nature of Thermal Spray Coatings with grate interest and with real pleasure. No doubt, it could be recommended as a manual for engineers. As I have dealt for a long period with detonation spraying of coatings, I d like to remark some points at the mentioned text and to make some proposals.
1. Explaining the nature of coating failure, where the tensile stresses exceeds that of the bond strength or cohesive strength, you show two
right pictures, where the bending of the coating is directed to free surface of coating due to its cooling and solidification. I would agree with it, if the heat flow has the same direction, what could be in the case, for instance, if air cooling flow winds to the sprayed surface. In opposite situation, if cooling flow winds to the substrate and it s productivity enough for the heat flow to direct to the substrate, the coating bends tending to snuggle to the substrate. It s clear, that all said concerns to convex form of the substrate, which has to be cooled during spraying to achieve good adhesion strength. In opposite case, if, say, internal cylinder surface has to be coated, the last must be heated just before spraying to enable the initial expansion of the hole, which will follow the shrinkage as well as that of sprayed coating. This procedure of preliminary heating is necessary to avoid the coating detach after spraying.
Best regards

Follow Ups:
Surface Engineering Forum

Surface Engineering Message Board Archive

Surface Engineering Message Board Archive Index

Post A Message!

Gordon England Surface Engineering ForumPlease go to the new Surface Engineering Forum as this old message board is a read only archive. Please copy and paste relevant information or link to the page if you wish to reactivate a thread on the new forum.

Gordon England Independent Thermal Spray Coating Consultant
Telephone: +44 (0)1252 405186


Site Links


Nature of Thermal Spray Coatings

Surface Engineering in a Nutshell

Surface Engineering Forum

Thermal Spray Gun Repair Service

Plasma Consumable Parts

Thermal Spray Powder Supplies


Thermal Spray Coatings on Carbon and Glass Fibre Reinforced Polymers

HVOF Coating of Paper Making Roll

Abradable Coatings


Thermal Spray Processes:

Combustion Wire Thermal Spray Process

Combustion Powder Thermal Spray Process

Arc Wire Thermal Spray Process

Plasma Thermal Spray Process

HVOF Thermal Spray Process

HVAF Thermal Spray Process

Detonation Thermal Spray Process

Plasma Flame Theory

Cold Spray Coating Process

Wear and Use of Thermal Spray Coatings

Corrosion and Use of Thermal Spray Coatings

Glossary of Thermal Spray and Surface Engineering Terms

Image Directory for Thermal Spray Coatings

Plasma Gas Flow Information

Plasma Gas Flow Correction Calculator

Contact Form

Links to other interesting sites related to thermal spray and surface engineering

Reciprocal Links

Periodic Table of the Elements

SI Units

Calculators for Conversion between Units of Measurement

Hardness Testing

Surface Engineering Message Board Archive

Surface Engineering Message Board Archive Index

Photography Gallery2

Photography Gallery3

© Copyright Gordon England