One of the improvements that can be made to internal combustion engines, without significantly altering the structural elements, is increasing the temperature in the combustion chamber by coating its component elements with thermal barrier coatings (TBC). In this paper were analysed from the microstructure point of view the coating-substrate interfaces of three layers deposited by thermal spraying: S1 - Cr2C3 - NiCr, S2 - MgZrO - NiCr and S3 - ZrO - CaO. The investigations were performed by electronic microscopy on the cross sections taken from the samples after they were subjected to similar heating to the one produced during the operation. It has been observed that all three types of coatings have a much better density, are chemically stable and have good adhesion to the substrate, which recommends them for this type of use.

Surface engineering has been conquered in recent decades by the versatility of the layers produced by thermal spraying, both in terms of spraying methods, of the materials types and their applications. In some cases, the coatings can be subjected during operation to rolling contact fatigue, with the main wear factors: thermal spray coatings structure and state of stress and strain in the contact area. In this paper was studied how three types of coatings deposited by APS (Atmospheric Plasma Spray) behaved at the contact fatigue tests. Subsequently they were carried out simulation of pressures and von Mises stresses distribution. It has been observed that the presence of asperities on the surface causes the development of local micro-contacts and therefore high values of pressure and local stresses in the vicinity of the surface.

Because the surface engineering is becoming an increasingly viable alternative to the constructive changes made to improve the efficiency of internal combustion engines, have been proposed and tested various types of coatings of some organs of internal combustion engines. One vital organ is the engine valves, which is subjected during operation to combined thermal, mechanical, corrosion and wear solicitations, which are leading to severe corrosion and complete breakdown. In this paper were analyzed aspects of valves wear and the active surfaces were coated using the atmospheric plasma spraying method (APS) with two commercial powders: Ni-Al and YSZ. Microstructural analyzes were made on these layers and also observations regarding the possibility of using them as thermal barrier and anti-oxidant coatings.

Due to the development of thermal spray deposition technologies, thus obtained layers have more applications and fields of use. One of the coatings with increased application is the one produced from Ni-based self-fluxing alloys, which besides the good wear resistance, shows a satisfactory corrosion resistance. In this study it was observed the behavior of three types of coatings produced by Flame Spray method, both at wear and especially corrosion in the environment simulating acid rain. As a result of the experiments it was found that these layers became compact enough after applying the self-fluxing heat treatment, so in their structure are not present defects such as pores and micro-cracks, unmelted particles etc., which could be points of corrosion initiation.