The aim of this study is to improve the releasability of carbon fiber reinforced plastic (C-FRP) molds by depositing a plasma-sprayed Y 2 O 3 coating on working surfaces. Composite molds are considered for use in IC encapsulation. To promote adhesion, an interlayer, either copper or gradient yttria, is applied between the substrate and coating. The coatings deposited over gradient Y 2 O 3 performed better than coatings applied over copper due to the large reduction in thermal mismatch achieved with a graded thermal expansion coefficient. Preliminary releasability results show that the yttria coatings have high adhesion strength and the potential to uniformly reduce release forces between C-FRP surfaces and epoxy resins.

Nanocomposite epoxies are novel sealants developed especially for sealing metalized coatings. In order to test the corrosion protection performance of arc-sprayed aluminum coatings plus this sealer, steel panels were coated and placed in a corrosion test site on the East China Sea. Test panels were mounted in a marine atmosphere zone, seawater splash zone, tidal zone, and full-immersion zone. Several tests were conducted including corrosion and coating adhesion tests. This paper presents the results obtained from composite-coated steel panels after three years of seawater exposure.

Tensile testing of thermal spray coatings is currently covered by a variety of internal company specifications and generally by ASTM C-633. It is a highly recognized fact that liquid epoxies, on average, produce higher results in side by side comparisons with their film counterparts. However, the liquid epoxies show a higher standard deviation in those same comparisons. This raises questions about the interaction of liquid epoxies with porous thermal spray coatings. Tensile data from side by side comparisons was analyzed and optical microscopy work performed to determine how the epoxies affected the coatings and if the epoxy infiltration actually occurs. In the case of porous plasma coatings, it is shown that liquid epoxies penetrate into the coatings and, thereby, increase the apparent tensile strength.

Laser post-treatments and plasma-laser hybrid spraying processes are increasingly being used to extend the service life of thermal barrier coatings by making them more resistant to thermal shock. Studies show that laser-induced cracking plays a major role in the improvements achieved. The investigation of such modified layers can be difficult, however, because the stresses associated with metallographic procedures can alter the structural features of segmented microcracks and damage the specimen. In this research, laser treated and laser hybrid sprayed thermal barrier coatings are vacuum impregnated with fluorescent epoxy resins in order to study their microstructure and its relationship with thermal shock resistance. All relevant processes are described along with crack formation behaviors. Paper includes a German-language abstract.

This study investigates the effect of mounting materials on microstructure and property measurements obtained from thermal spray coatings. Various epoxies and embedding techniques are used and a wide range of layers are examined, including HVOF sprayed WC-Co, Cr 3 C 2 -NiCr, and Al 2 O 3 -TiO 2 ; plasma sprayed Cr 2 O 3 , YSZ, WC-Co, and Ni-Al; and arc sprayed copper and silicon bronze. Image analysis measurements of area percent porosity, thickness, lamellar spacing, and unmelted particles and the results of hardness tests show substantial variation relative to the method used to encapsulate soft and porous coatings. Results indicate that the ideal mounting system for thermal spray coatings would consist of a low viscosity epoxy, to maximize penetration depth, and a high cured hardness, for adequate protection of surfaces and open porosity of hard coating materials. Paper includes a German-language abstract.

Different oxides layers have been studied by friction in natural sea water medium under the same conditions (Cr 2 O 3 , Al 2 O 3 , Al 2 O 3 + Cr 2 O 3 ). The evolution of different parameters have been analyzed: friction coefficient, electrochemical potential, degradation of the layers in the contact, impedance spectroscopy. The main result observed is concerned by the cracking of the coatings under stresses, in such a way interconnection paths are rapidly present between the substrate and the sea water medium through the layers. The coating impregnation process by epoxy, before the tribocorrosion tests, improve the protection of the substrate against the corrosion.

Plasma spray deposition of epoxies under normal conditions produces coatings with low wear resistance. The research shows that the difficulty in achieving satisfactory properties is a result of the rapid heat flow from the coating to the substrate, which suppresses the crosslinking reaction. The results indicate that the use of substrate preheating or ceramic undercoats enhances the wear resistance by promoting the curing reaction during spraying.