STUDIES OF THE PARTICLE-IMPACT PROCESS FOR APPLYING CERAMIC AND CERMET COATINGS
Abstract
A basic study was made of the particle-impact process for applying coatings of aluminum oxid with rod and po der-type flame-spraying guns. The coatings were found to consist primarily of the softer eta phase rather than the harder and more stable alpha form of alumi a. It was established that the eta phase forms because of the high quenching rates, of the order of 800,000 C/sec. on a stainless steel substrate, and 34,000 C/sec. on glass. Size and velocity measurements were made for particles from both gun types High-speed motion pictures showed that the powder guns sprayed particles continuously; the rod gun in bursts. A chemical bond sufficient to withstand interfacial stresses without spontaneous failure was developed between the coating and smooth glass substrates, but never between the coating and smooth metal. It was shown that the apparent bond strength between the coating and iron increased exponentially with increasing roughness of an iron surface, rather than linearly.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1961
- Accession Number
- AD0266381
Entities
People
- A. G. Eubanks
- A. W. Crigler
- D. G. Moore
- H. R. Thornton
- W. D. Hayes Jr.
Organizations
- National Institute of Standards and Technology