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In our present work, alumina/BNNTs and alumina/MoS 2 coatings were deposited onto stainless steel substrates by solution precursor high velocity oxy-fuel thermal spraying. The phase evolution, microstructure and tribological properties of the two kinds of coatings were studied. Investigation of the phased content showed that Al 2 O 3 , BN and MoS 2 survived in the coatings after being sprayed with SHVOF technology. Cross-section images of the coatings showed that the interface between the coating and the substrate was well bonded, and there were no obvious particle inclusions and defects at the interface. The top morphology of the coatings exhibited certain degree of particle deformation, which was conducive to the formation of a more compact coating with less porous and better bonding strength with the substrate. Dry sliding tests showed that alumina/BNNTs and alumina/MoS 2 coating improved the tribological properties of the samples and they were suitable for low load friction conditions (5 and 10 N). A crack evolution model was proposed to analyze the failure of coatings. This work could provide a reference for the application of the two coatings in the field of friction and wear. • Alumina/BNNTs and alumina/MoS 2 were deposited onto a stainless steel substrate using SHVOF thermal spraying. • The top morphology of the coatings exhibited a certain degree deformation of the particles. • The wear mechanisms of the coatings were dominated by coating peeling off, adhesion and abrasive wear. • A crack evolution model was proposed to analyze the failure of coatings. [ABSTRACT FROM AUTHOR]

According to the tensile crack model, a simple model for tribological behaviors of diopside/AlTiB toughened alumina matrix ceramic guideway materials, predicting the relationship between load and wear rate, was presented. 45# steel ring was used as the counterpart. Mechanical properties and wear properties of the guideway materials under different loads were investigated. SEM micrographs of wear tracks on typical specimens were studied. Results showed that the experimental data described in this paper were in accordance with the theoretical prediction. Introduction of diopside and AlTiB master alloys in alumina matrix ceramic guideway materials improved their mechanical properties, friction and wear properties. The wear rate of pure alumina was in the order of 10 −15  m 3 /N·m while that of guideway materials toughened by diopside and AlTiB master alloys was in the order of 10 −16  m 3 /N·m. The wear mechanisms of pure alumina may be brittle fracture and grain pull-out. The dominant wear mechanisms of alumina matrix ceramic guideway materials toughened by diopside and AlTiB master alloys may be mechanical interlocking and plastic deformation combined with a little micro-fracture and grain pull-out. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, diopside and AlTiB were simultaneously introduced in alumina using pressureless sintering. Microstructures of the composites were observed at a given temperature of 1520°C and different holding time. Sintering densification process of the composites was studied. Experiments were performed in the temperature at equal increments: 1420, 1520, 1620 and 1720°C, and with four holding times, i.e. 100, 140, 180 and 220min. The apparent activation energies of 17.7–28.8kJ/mol for alumina matrix ceramic materials were calculated by least squares. The sintering kinetic equations were deduced. Results showed that the sintering of monolithic alumina was controlled by volume diffusion, and that of alumina matrix ceramic materials doped with diopside and AlTiB was controlled by grain boundary diffusion and volume diffusion. [Copyright &y& Elsevier]