Engineering topics

Mcdonald, Glen

Publications and source records attributed to Mcdonald, Glen.

2 records

NASA NTRS1987

Interface roughness effect on stresses in ceramic coatings

This paper presents an analysis of the interface stress in plasma-sprayed zirconia coatings. The stress distributions along smooth and rough interfaces were calculated for perfectly bonded materials. The effect of mechanial interlock along the interface was also calculated. The interface stresses for noninterlocking interfaces were consistently higher; the interlocking interfaces showed high stresses in small regions only.

Mullen, Robert L.↗

NASA NTRS1987

Some adhesion/cohesion characteristics of plasma-sprayed ZrO2-Y2O3 under tensile loading

A set of 12.7 mm diameter stainless steel tubes were coated with ceramic and expanded. The bond cast was 0.08 to 0.13 mm NiCrAlY with 0.38 mm of ZrO2-8Y2O3 ceramic. Upon pressurization, the tube substrate yielded and overstressed the coatings in tension. The coatings cracked (i.e., they failed) but did not come off the tube. These results demonstrate that tensile failure of plasma-sprayed coatings is not catastrophic as is compressive failure, which leads to spallation.

Mullen, Robert L.↗