Study on Strength and Stiffness of WC-Co-NiCr Graded Samples

Abstract

This work deals with the investigation of the strength and the stiffness of samples built of step-variable functionally graded material (FGM). The considered FGM samples consist of two main components: WC and NiCr with some content of Co as a conjunction of structure. The samples were fabricated on the basis of the detonation gun layer deposition method which is regarded as a novelty in the case of FGM production. The analyzed samples possess a finite number of layers with different varying fractions of each constituent across the wall. The basic tests of bending were conducted to assess the influence of used components in adequate proportions on the stiffness and the total strength in bending. In addition, to validate the numerical approach, simulations of samples under similar loads with truly reflected material distributions were carried out. The material properties of components were determined due to micro-nano-hardness by instrumental indentation techniques. The numerical calculations were performed with the use of the material characteristics for each material and with a consideration of large deflections. Furthermore, by means of an electron microscope, the composition of materials and distribution of chemical elements across the thickness of samples were examined. This paper reveals the experimental results of FGM samples manufactured by detonation gun layer deposition which allows the creation of layer by layer moderately thin-walled structures. It was shown that the indentation method of a determination of Young's modulus gave higher values in comparison to values attained in the bending test. Moreover, it was stated that a modelling of FGM still requires the study of each layer separately to clearly predict the strength of the whole FGM structure.

Morphological Analyses of W/Cu Functional Graded Materials Obtained by Conventional and Spark Plasma Sintering

“…Due to their high performance and many of their functionalities, FGMs have been successfully used in the construction of new generations of spacecraft. The most familiar FGMs are those composed of refractory ceramic materials and metals because they combine properties very well, such as resistance to high temperatures and wear and oxidation offered by ceramic materials with properties such as mechanical strength, machining, and toughness offered by metallic materials [10]. Due to their graded transition, another very important field of application of FGMs is that of ceramic coatings, where there is a need to reduce the stress concentrations and to increase the fracture strength [11][12][13][14].…”