Influence of Heat Treatment on Phases, Microstructures and Mechanical Properties of Laminated Fabric (SiC and Aluminosilicate)/Mullite Matrix Composites

Abstract

Oxidation resistance of SiC satin fabric (2529 vol÷) or aluminosilicate plain fabric (2533 vol÷)/mullite matrix porous composites was investigated at 10001200 C in air for 24 h using thermogravimetric analysis. The composites were produced by a polymer impregnation and pyrolysis (PIP) method using a mullite precursor solution of the mixtures of Si(OC 2 H 5 ) 4 and Al(NO 3 ) 3 . The oxidation rate of the sintered SiC bers with a stoichiometric SiC composition and wellcrystallized microstructure was controlled by the diusion process of gases through dense SiO 2 layer formed on the SiC surface. The activation energy for the oxidation of the SiC bers was 299 kJ/mol. This value was close to the activation energy for the diusion of oxygen atom in silica glass. The SiC satin fabric/mullite matrix composite heated in an Ar atmosphere showed pseu doductility due to the delamination along the fabric layers. The four pointexural strength decreased slightly with increasing heat treatment temperature. However, the composite heated in air at 11001200 C showed brittle fracture behavior without delamination because of the increased strength of interfacial bond between the oxidized SiC bers and mullite matrix. On the other hand, the amorphous aluminosilicate bers/mullite matrix composite showed little weight change during the heat treatment at 10001200 C. Crystallization of mullite occurred in the mullite precursorderived amorphous solid and aluminosilicate bers at 1100 and 1200 C in air, respectively. However, no microstructural change was observed in the heat treated composite. The signicant pseudoductility and strength of the aluminosilicate plain fabric/mullite matrix composite were maintained after the heat treatment. The fracture energy increased with increasing heat treatment temperature.

Influence of Heat Treatment on Phases, Microstructures and Mechanical Properties of Laminated Fabric (SiC and Aluminosilicate)/ Mullite Matrix Composites (Part 2)

“…The weight of the SiC fiber/mullite matrix composite was almost constant at a temperature lower than 1300 C but decreased greatly at 14001500 C. As a result, the relative density (72.2÷) for the asproduced composite decreased to 61.8÷ after the heat treatment at 1500 C. Figure 2 shows the Xray diffraction pat terns of the SiC fabric/mullite matrix composite heated at 13001500 C for 24 h in an Ar atmosphere. The mullite precursor showed galumina phase after the heat treatment for 24 h at 10001100 C in an Ar atmosphere and crystallized to mullite at a temperature higher than 1200 C. 41) As seen in Fig. 2, the composites heattreated at 1300 and 1400 C con sisted bSiC and mullite phases.…”

“…Crystallization of mullite occurred in the mullite precursorderived amorphous solid and alumino silicate fibers at 1100 C and 1200 C in air, respectively. 41) However, no microstructural change was observed in the heattreated composite. The significant pseudoductility of the aluminosilicate fabric/mullite matrix composite was main tained after the heat treatment.…”

“…However, the composites heated at 10001200 C showed little change in the weight, phases and microstructures when compared with those for the asproduced composite. 41) No difference was found among the Xray diffraction pat terns of the aluminosilicate fabric/mullite matrix composite after the heat treatment at 13001500 C. Figure 5 shows the microstructures of the aluminosilicate fabric/mullite matrix composite heattreated at 13001500 C in air. The amorphous mullite precursor and aluminosilicate fibers crystallized into mullite at 1100 C and 1200 C, respectively.…”

“…In our previous work, 41) the SiC fabric or aluminosilicate fabric/mullite matrix laminated composite was heattreated at 10001200 C for 24 h in air and in an Ar atmosphere. It was found that the heat treatment in an Ar atmosphere gave little influence on the phases and microstructures, and slightly decreased the bend strength of the SiC fabric/mullite matrix composite.…”

Preparation and properties of aluminum phosphate‐polyethersulfone laminated composites modified by aluminosilicate fiber fabric

“…In addition to the aforementioned fillers, aluminosilicate fiber (AF) exhibits a lot of distinguishing features, such as high specific strength, strong wear resistance, good thermal stability, and low cost, which makes it as the popular reinforcing fiber in the preparation of thermal insulating materials . Aluminosilicate fiber paper (AFP) and aluminosilicate fiber fabric (AFF) are also the common reinforcement materials, as they can provide effective enhancements in multidirections together with satisfactory stability in mechanical performances . To the best of my knowledge, the profound researches about the preparation and dielectric properties of AlPO 4 ‐PES composites reinforced by AFP and AFF have not been reported so far.…”