Investigation of boron doped Ni3Al coating of austenitic stainless stell

With this method high-temperature corrosion resistance can be improved in the very economic and rapid way. Moreover, the method does not require a special apparatus and equipment and thus it can be applied even an ordinary place. Austenitic stainless are the steels which contains %12 Cr % 8 Ni. Microstructure of these steels can not be changed they have a by heat treatment. Fully austenitic structure. The main problem encountered in steels is carbides forming between 900 and 500 ºC and sigma phase, with high Cr contents Carbides precipitates in the grain boundaries and lead to a grain boundary corrosion (reducing the amount of Cr). Therefore, during cooling, these temperature must be passed rapidly. Austenitic stainless steels are used in the areas such as the major, medical, kitchen supplies, food, energy and shipping industry. Increasing the wear and corrosion resistance of these steels will expand the application fields. For this purpose, so far paint, polymer coating and ceramic coating and surface modification processes have been used in studies. A potantial application to improve high temperature wear and corrosion resistance is to coat the surfaces of this materials with a intermetallic compounds. Nowadays, a lot of work have been done in this field. Vapor phase deposition, powder spraying, laser spraying, TIG methods are applied, as coating methods. Recently, as a new method, SHS (Self Propogating High Temperature Synthesis) namely high-temperature synthesis method has been used for the self-advancing. SHS, for surface coating. It is an economic and easy method similar to thermit reaction in which an exothermic reaction provides forming intermetallic and welting the substrate surface with a flame propogation after the first ignation. The reaction created during the reaction increases the temperature up to the melting temperature of the compound. The reaction rate is very high. Therefore, using the heat of reaction both to form the compound and joint the compound with the substrate is the principle of this method. In this study, AISI 304 austenitic stainless steel material, the method of SHS powder coated Ni3Al micro-structures and micro-hardness values of the materials investigated the effects of production parameters. The effect of the type of stainless steel as a coating material during coating and metallic powders to be used is chosen as variable parameters. Microhardness tests were applied to the samples to determine the mechanical properties of coated materials. After the study, the coating of stainless steel type of material chosen by the method of SHS effect and the variable parameters of metallic powders to be used as a coating material to determine the most appropriate one. In the first part of this study is made of an introduction. In the second part of austenitic stainless steels is presented to stainless steels. The third section provides information on compounds to metals. The fourth chapter provides information on aluminum-based intermetallic compounds. In the fifth chapter provides information on the formation mechanism of nickel-aluminum intermetallic phases. The sixth chapter provides information on the processing of nickel-reactive aluminates. Nickel aluminide coatings are given information about the thermodynamics of the seventh chapter. Experimental studies are examined in detail in the eighth section, which were analyzed experimental results. Working at the end of the last section is obtained the ninth overall results. Keywords: SHS, AISI 304L, Ni3Al, Coating, Intermetallic