Re: T800 Coating Thickness limit by HVOF

Posted by Alex ( on 01:38:13 31/03/06

In Reply to: Re: T800 Coating Thickness limit by HVOF posted by Alexei Goncharov

Thanks for all the recommendation.
To update, I have tried some preventive action and seems the lifting or delamination has been improved significantly.
1. As recommended by Gordon, I have put part temperature monitoring into place, making sure that the part temp. would not exceed 120oC at all time. stop-spray method,for sufficient part cooling-off period.
2. I make sure the preheating is done with the preheating temp. of 120oC~~130oC. Would it be ok? too much or higher better?
3. I have changed corrodum grit size from 60 to 46, creating a much rougher surface. and make sure all best practises observed after grit blasting. And make sure all edges are blasting effectivel with Ra above 150 uin.
4. Use M.E.K to wipe the part if any touching is done to remove contamination.
5. I have also chamfered the edges to about 30o. As the edges of flange thickness is limited, so, it's hard for me to have a 45o chamfering. What would be the best undercutting or chamfering angle in this case?
6. Also, I practise clearing of overhang coating at each stop(cooling) to allow exccesice ooverhang coating build-up.
These area some practice I would like to share to have put a stop to the lifting problem.
The next problem I have is the edges chippings during benching of the overhang coating. I m still trying to solving this problem like reviewing the benching methods and so on. Any opinion and advice on this area?
Thanks for all the advice.
Alex Chan

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