Microwave Detection of Defects and Inhomogeneities in Low Pressure Injection Moulded β‐TCP Ceramic

Abstract

In Figure 6 the elastic constants and the strength dependent on the fiber-to-loading deviation are shown. It becomes obvious that the model describes the experiments very accurately.Conclusions: Based on the continuum damage mechanics and a plasticity model which is linked to the progress of damage it is possible to describe the mechanical behavior of ceramic matrix composites with weak and porous matrices under tensile loading with different fiber orientation. The investigated C/C material behaves strongly anisotropic due to the reinforcement by a two-dimensional fiber weave. Damage tolerant mechanical behavior and high strain to failure is realizable due to the low modulus and strength of the matrix. The critical damage processes and failure mechanisms are evaluated by quasistatic tensile tests with different fiber orientations which are well described by the proposed model. This model allows now to predict the material behavior in any other loading direction. The conformity of experimental and theoretical results shows the capability of the model which can now be applied for other composites with porous matrix and strong fibers.The feasibility of a nondestructive microwave inspection to detect internal processing defects in low pressure injection moulded ceramic parts was investigated. A b-TCP (b-tricalcium phosphate, Ca 3 (PO 4 ) 2 ) slurry with paraffin, ethylene vinyl acetate copolymer and stearic acid as binder system was injection moulded with a pressure of 0.2 MPa and subse- COMMUNICATIONS

Preceramic Paper‐Derived Ceramics

“…Characterization of the spatial variation of density, that corresponds directly to the filler distribution in the sheet, is of particular importance in order to control shrinkage upon sintering and to avoid residual stress formation, which can cause delamination during processing of multilayer laminate ceramics. Figure 7(a) shows a transmission microwave (90 GHz) amplitude scan 37 of an alumina‐filled preceramic paper. The paper sheet investigated was then subdivided into pieces of 10 mm × 10 mm, and the geometrical density of each individual piece was determined by the Archimedes method for reference.…”

“…a) shows a transmission microwave (90 GHz) amplitude scan37 of an alumina-filled preceramic paper. The paper Compositional diagram showing the range of preceramic paper compared with common writing paper.…”