1. Research project objectives/research hypothesis
Nowadays, because of high energy demand in various industries and everyday life, the efficiency of energy production is a crucial economic factor. In order to improve these technologies, innovative composite materials have been proposed. They combine the features of ceramic and metallic materials. The use of such materials makes it possible to increase the process efficiency by raising the working temperature of the engine. Additionally, new type of materials can reduce costs of turbine blade manufacturing.
Planned research in focused on the development of a metal matrix composite with ceramic reinforcement using rapid prototyping technology, which is commonly referred to as 3D printing. Obtained material could be used in the production of turbine blades exposed to destructive factors. High temperature corrosion together with erosion and mechanical tensions are defined as fretting. It leads to the wear of the surface of materials due to the formation of microcracks and scratches, which later may proceed to destruction of the material. Due to its high temperature properties, nickel based alloys - Inconels were selected for the matrix. They are characterized by high fatigue strength, plasticity, thermal stability and resistance to corrosion and erosion. That properties are the reason why Inconels are commonly used in heat exchangers, aerospace, chemical and power industries.
Ceramic reinforcement in form of carbides will be used to improve the performance of Inconel. Creep and abrasion resistance together with high hardness are the reason why they were selected. The chosen laser cladding technique, offers great flexibility in designing the final properties of the material by fully controlling the process parameters. This allows for obtaining a product that is specifically prepared for intended work environment. In addition, 3D printing methods give us the possibility to produce parts with complicated geometry.
2. Research project methodology
The proposed research will use commercially produced powders: nickel based - Inconel, and selected carbide of various grain sizes. The whole project is divided into 4 stages:
I. The first stage is the preparation of substrate mixtures. Commercially available metallic and ceramic powders will be mixed and then homogenized in a ball mill with resin addition as a binder. An analysis of morphology and elemental composition of the grains will be made by scanning electron microscopy equipped with an EDS microanalyzer. Laser diffraction will be used to determine particle size distribution while the BET method will allow to characterize the surface area of the powders.
II. The second stage is the production of polycrystalline composite coatings. Protective coating will be applied to a properly prepared substrate by laser cladding. The process requires optimization of its parameters such as: laser power, head travel speed, beam focal length, cooling rate and the powder feed ratio.
III. The third stage focuses on the analysis of the obtained material. In order to examine the quality of the composite, it is necessary to carry out phase analysis by means of X-ray diffraction, microstructural analysis with particular emphasis on the shape of the grains, concentration and structure of the grain boundaries. These observations will allow to determine the crystallization mechanism that occurs during rapid solidification. The evaluation of the surface roughness will be made with a confocal microscope. Hardness of composite will be tested. Due to the potential harsh work environment, the wear resistance, thermal conductivity, thermal stability, thermal expansion and corrosion resistance to oxygen will be examined.
IV. In the fourth step, the kinetics of phenomena occurring in the material during the application of the composite coatings by laser cladding will be described based on obtained results.
3. Expected impact of the research project on the development of science, civilization and society
Based on previously mentioned facts, we believe that the development potential of the project results is high. It concerns the quantitative production of turbine blades for the energy industry, which is a strategically important sector of the economy for the country. The planned project is certainly innovative. In the future, the results of the work may be applied to the production of not only the engine or turbine components, but also to provide the physicochemical basis for the production of many other equipment. The obtained results may contribute to the development of rapid prototyping methods.