The article presents experimental studies of composite powder materials for plasma spraying, obtained by the method of diffusion doping of powder materials based on austenitic steels. It is indicated that the main factors forming the diffusion layer on a powder material are a composition of the required saturating medium, treatment temperature and duration of chemical and thermal exposure. Creation of single-phase diffusion layers is possible only in the case of a minimum level of temperature-time characteristics during heat treatment. This is also facilitated by the use of media with a low concentration of boron and introduction of additives inhibiting saturation process (such as carbon, aluminum, silicon) into a saturating mixture of powder. Structure and composition of powders have been thoroughly investigated with the help of X-ray microanalysis that has made it possible to study location of elements contributing to powder alloying and micro-durametric characteristics. A component of high-boride phase is increasing due to higher degree of powder material alloying. Significant changes in phase composition, as well as the chemical one, are noticeable in diffusion processing of the following alloyed powder materials: РR-Х18N9, РR-Х18N10, РR-Х18N15. Free carbon being displaced by boride into a transition zone creates dispersed complex carbide compounds with chromium. This is confirmed by distribution nature of carbide-forming components in a powder particle. All carbide-forming elements have characteristic concentration peaks-bursts in contrast to non-carbideforming silicon. Silicon is practically not present in the considered FeB phase and it is found only in a very small amount in the studied Fe2B phase; it is pushed aside by high-boride phases to a sublayer. The change in microhardness of the FeB and Fe2B phases under study is associated with dissolution of corresponding alloying elements in them and distortions of a crystal lattice in borides. A similar phenomenon is also characteristic for saturation while using boron or while making chemical and thermal treatment of alloyed steels, it has been noted in a number of studies. The increase in microhardness of a particle nucleus during its boriding is caused by displacement of carbon and alloying elements by growing front of boride phases. A core zone moves with an increased microhardness to a particle core while increasing temperature mode and time of boronization and up to realization of the effect with counter diffusion.

The paper describes investigations on wear-resistant coatings from diffusion-alloyed austenitic steel obtained while using plasma spraying and subsequent laser processing. It is common knowledge that majority of machine parts and equipment has been out of service due to wear of surface layer. Application of diffusion-alloyed powder ПР-Х18Н9 based on austenitic steel while using combined technology including plasma spraying and laser infusion makes it possible to obtain qualitative coatings with high operational characteristics. The coating has a homogeneous structure with characteristic dispersive finely-dendrite formation. While using various powder boronizing modes and laser processing it is possible to control a porosity  (0,23–4,70 %) because the given factor is considered as an inherited parameter and it is influenced not only by laser processing characteristics but by powder boronizing time. It has been established that  the least deformations and internal stresses are formed in the coating in the case when self-fluxing diffusion-alloyed powder has been applied for 3 hours.  It has been revealed that there is a sharp increase in micro-hardness at the depth of 150-400 µm from the surface for a specific energy of 100-300 J/mm2 regardless of boronizing time. Coatings can be successfully applied in industry because after laser infusion the required mechanical processing of parts will not worsen operational characteristics when less hard coating layer is removed. Tests of parts under conditions of dry sliding friction without lubrication  have shown an increase of wear-resistance by 3.0-3.2-fold while preserving corrosion-resistance.

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The analysis of physical and chemical processes and mechanisms of structural engineering in ceramic materials science and technology of technical ceramics when creating materials for various technical purposes is presented. Ill. 1. Ref. 16.

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