Particle reinforcement

There are three kinds of metal-matrix composites distinguished by type of reinforcement particle-reinforced MMCs, short fiber- or whisker-reinforced MMCs, and continuous fiber- or sheet-reinforced MMCs. Table 1 provides examples of some important reinforcements used in metal-matrix composites as well as their aspect (length/diameter) ratios and diameters. 

The general range of values for particle-reinforced alurninum-type MMCs is between 15—30, whereas short fiber- or... 

In aerospace appHcations, low density coupled with other desirable features, such as tailored thermal expansion and conductivity, high stiffness and strength, etc, ate the main drivers. Performance rather than cost is an important item. Inasmuch as continuous fiber-reinforced MMCs deUver superior performance to particle-reinforced composites, the former are ftequendy used in aerospace appHcations. In nonaerospace appHcations, cost and performance are important, ie, an optimum combination of these items is requited. It is thus understandable that particle-reinforced MMCs are increa singly finding appHcations in nonaerospace appHcations. 

The above model has been successfully used to describe the thermomechanical behaviour of iron-particle reinforced resins. More precisely, the importance of this model is that it provides a quantitative means for assessing the adhesion efficiency between the phases and its effect on the thermomechanical properties of the composite. Moreover, by using this model the thermomechanical behaviour, as well as the extent of the mesophase developed in particulates could be described. The... 

E. Haque. Physicochemical interactions between montmorillonite and polymerizing systems Effect on particle-reinforced composites. PhD thesis. Rice Univ, 1986. 

Particle-Reinforced Composites—Large-Particle Composites 559... 

Todd, R.I., Morsi, K. and Derby, B. Neutron diffraction measurements of thermal residual microstresses in ceramic particle reinforced alumina , Brit. Ceram. Proc. 57 (1997) 87-101. 

Jin, Z-H., Batra, R.C. (1999), Thermal shock cracking in a metal-particle-reinforced ceramic matrix composite , Eng. Fract. Mech., 62, 339-350. 

Over the last decade, considerable efforts have been committed to the toughening of sialons and substantial progress has been achieved using various reinforcements. According to the form of reinforcement, sialon composites can be classified as either particle reinforced, discontinuous fibre (whiskers/ short fibres) reinforced, or continuous fibre reinforced. 

Toughening mechanisms in a/p-sialon composites are similar to those operative in second-phase particle reinforced composites, but, rather than the deliberate addition of a second phase, a/P-sialon composites are fabricated by simultaneous crystallisation of the two solid solutions a- and P-sialon from a eutectic composition liquid. This requires careful design of the starting composition which is usually located within the (a + P)-sialon region of the a-sialon plane as illustrated in Fig. 18.1. 

Rouxel and Verdier (1996) studied the viscoplastic forming and the crystallization ranges of SiC particle reinforced Y-Mg-Si-Al-O-N glass composites produced by hot-pressing at 1050°C. Crystallization starts beyond 1050°C, with spinel, MgAl204, enstatite, MgSi03, and y- and 8-Y2Si207 as... 

SiC particle reinforced oxynitride glass composites have been investigated and found to have higher values of mechanical properties which are related to the volume fraction of SiC inclusions, provided that SiC-glass reactions can be avoided. These composites have been shown to be suitable for viscoplastic forming. 

Rouxel, T., Verdier, P. (1996), SiC particle reinforced oxynitride glass and glass-ceramic composites crystallization and viscoplastic forming ranges , Acta Mater., 44, 2217-25. 

D.J. Lloyd Particle reinforced aluminium and magnesium matrix composites. Int. Mater. Rev. 39, 1-23 (1994)... 

G. Bao, J. W. Hutchinson and R. M. McMeeking, Particle Reinforcement of Ductile Matrices against Plastic Flow and Creep, Acta Metallurgica et Materialia, 39, 1871-1882 (1991). 

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