Static Mechanical Characterization of Ceramic Matrix Composites (CMCs)

Abstract

This article reviews the most common standard tests that are used in characterization of ceramic composite materials. Standard static tests in relation to ceramic composites are shortly presented, also including sampling aspects. The main objective of the material characterization is to determine the functional properties in real systems, but the initial testing starts in the lab environment on specific samples that simulate work conditions. Mechanical properties like strength, hardness, and toughness are the most influential factors that affect the material applications. The most common mechanical tests are tensile, compressive, bending and shear testing of both the composite and reinforcing phases (fibers). Tensile testing provides properties like yield strength, tensile strength, elongation and modulus of elasticity. Compressive properties include modulus of elasticity, compressive yield strength, and compressive strength. The bending test can be performed as three-point or four-point bending. Shear strength is very important material property, especially for fiber-reinforced composites, and standardized shear tests consider several possible methods: Rail Shear Test Method; V-Notched Rail Shear Test Method; [±45]ns Tensile Shear Test Method; Short-Beam Shear Test Method. Mechanical testing of the fiber/matrix interface can be realised by three common methods: Curved-neck sample test; Bending test (Transverse or Longitudinal); Pull-out and push-out fiber test. Short list of the selected ASTM standards in relation to ceramic matrix composites is also included. There are numerous mechanical tests, also including non-standard ones, depending on the application of the composite. Even though mechanical tests are the most important in investigation and development of existing and new composite structures, there is still a need to define the most optimal test methods for new hybrid composites and to further develop standardized mechanical tests.