(03-10-2009, 04:29 PM)M Brecker Wrote: This is great information. I appreciate it very much. I understand the the sealant penetrates through the porosity in the coating. Our chrome oxide is machined to specific dimensions. Won't most of the sealant be removed? How does a soft sealant provide strength in wear type applications?
MBecker,
The saelant is applied to the flame srpayed coating , in the "AS SPAYED" condition, or prior to the grinding operation. This allows for the maximum sealing capabilities of the ceramic solution. After grinding to size the ceramic solution is applied 2 to 3 more applications. If you grind the part first you take a huge chance of smearing the coating, thus covering porosity or cracks preventing the ceramic solution form penetrating and sealing the flame sprayed coating. As the coating wears, this porosity can be opened to the environment and the failure process starts again.
Specifc to your question the sealant provides minimum wear characteristics in relationship to the flame sprayed coating. The sealant main purpose is to prevent a corrosive environment from penetrating into the coating and attacking the substrate, which ultimately undermines the flame sprayed coating and then failure occurrs. Secondly, you will recognize an increase in bond strength as the sealant will bond to the flame Sprayed coating as well as the substrate. You will recogognize a reduction in friction. Tests on Tungsten carbide have shown a 30% reduction in weight loss in ASTM G 65 wear testing. So there is some wear protection.
Kevin.tackett@bodycote.com. Send me an email anytime. I like to help.
(03-11-2009, 01:36 PM)KevinT Wrote: (03-10-2009, 04:29 PM)M Brecker Wrote: This is great information. I appreciate it very much. I understand the the sealant penetrates through the porosity in the coating. Our chrome oxide is machined to specific dimensions. Won't most of the sealant be removed? How does a soft sealant provide strength in wear type applications?
MBecker,
The saelant is applied to the flame srpayed coating , in the "AS SPAYED" condition, or prior to the grinding operation. This allows for the maximum sealing capabilities of the ceramic solution. After grinding to size the ceramic solution is applied 2 to 3 more applications. If you grind the part first you take a huge chance of smearing the coating, thus covering porosity or cracks preventing the ceramic solution form penetrating and sealing the flame sprayed coating. As the coating wears, this porosity can be opened to the environment and the failure process starts again.
Specifc to your question the sealant provides minimum wear characteristics in relationship to the flame sprayed coating. The sealant main purpose is to prevent a corrosive environment from penetrating into the coating and attacking the substrate, which ultimately undermines the flame sprayed coating and then failure occurrs. Secondly, you will recognize an increase in bond strength as the sealant will bond to the flame Sprayed coating as well as the substrate. You will recogognize a reduction in friction. Tests on Tungsten carbide have shown a 30% reduction in weight loss in ASTM G 65 wear testing. So there is some wear protection.
Kevin.tackett@bodycote.com. Send me an email anytime. I like to help.
PS. I forgot to add the most important part. The sealant has a Microhardness value of 2850 HV and a macro hardness in the 1000 to 1500 HV range. This is not a soft sealant as some use. Also, this sealant can and is working in temperatures +2000F with no deleterious results