The use of PAP-2 aluminium powder when manufacturing powder composites: the features of technology, structure, physical and mechanical properties of the composites. Part 2: Study of composite properties and structure

Abstract

This paper shows the possibility to reinforce the Al/Al2O3 laminated cermet matrix with metal fibres of rapidly solidified alloys (steel, titanium, and aluminium), as well as with discontinuous duralumin chips. Several energy-intensive destruction mechanisms resulted in the maximum reinforcement effect achieved by using titanium and steel fibres with their content of 20 and 10 vol.%, respectively. The resulting composites have the following properties: ρ = 2,30÷2,85 g/cm3; σbend = 180÷250 MPa; K1s = 7,5÷15 MPa·m1/2 and KSU = (18÷35)·103 J/m2. The composite «Al/Al2O3 – Ccoke residue» has ρ = 2,21÷2,23 g/cm3 with a very low sliding friction coefficient of 0,17 (the counter-face was a ball made of Steel ShKh-15 loaded by 1 N). The oxide-adhesive type of bonding is formed in the «Al/Al2O3 – alumina grains» composite which allows removing spent grains from the grinding work zone and achieving the self-sharpening mode. The material containing kaolin fibres is an ultra lightweight (0,25–0,5 g/cm3) ceramic insulation with λ = 0,07÷ ÷0,2 W/(m·К) in the 20–1000 °C range. The material comprising alumina spherulites combines both relatively high hardness (σbend = = 10÷50 MPa) and porosity (42–52 %) with high thermal stability which is the result of rapid elimination of the temperature gradient from micron-size structure elements.