TRANSMISSION ELECTRON MICROSCOPY OF PLASMA SPRAYED CERAMIC DEPOSITS

摘要

Microstructure of plasma sprayed deposits is usually very complex containing solidified lamellas, microcracks, unmelted particles and small voids. Internal structure of solidified lamellas is often composed of narrow columnar grains or can be amorphous. A powerful tool to study fine microstructures of the coatings and the complexities of the substrate/coating interfaces is the Transmission electron microscope. However, preparation of electron transparent foils, which require thickness below 500 mm, is very difficult especially in case of ceramic coatings on metal substrates. Traditional sample preparation techniques rely on extended ion-milling that tends to generate ion-induced artifacts in the samples. The modified wedge polishing technique introduced in the paper significantly reduces the time required for final ion-milling step. Several samples prepared by the wedge polishing method are documented.