Friction and Wear Behavior of Alumina Composites with In-Situ Formation of Aluminum Borate and Boron Nitride

Abstract

Wear and friction properties of Al2O3 composite reinforced with in-situ formed aluminum borate (9Al2O3·2B2O3) and hexa-boron nitride (h-BN) have been investigated. The initial constituents for the composites were Al2O3, AlN, and H3BO3. The H3BO3 was used as a source of B2O3, where B2O3 reacted with AlN and Al2O3 to form in-situ h-BN and 9Al2O3·2B2O3. Based on the thermodynamic calculation and phase transformation, four different compositions were selected. First, the powders were mixed by ball milling followed by compaction at 10 MPa. The compacted pellets were sintered at 1400 °C in vacuum. The composites were characterized using X-ray diffraction followed by hardness measurement and reciprocating sliding test against alumina and steel balls. The X-ray diffraction results revealed the formation of in situ phases of 9Al2O3·2B2O3 and h-BN that improved the tribological properties. By comparing the tribological performance of different composites, it was found that the hard 9Al2O3·2B2O3 phase maintains the wear resistance of composites, whereas the coefficient of friction is highly dependent on the counter ball. Against alumina ball, the lowest coefficient of friction was observed for the composites with maximum h-BN concentration and minimum aluminum borate concentration, whereas the opposite trend was observed against the steel ball.

Nanoenergetic Materials: Enhanced Energy Release from Boron by Aluminum Nanoparticle Addition

“…The higher extent of oxidation and the corresponding heat release from BAL10 ( Figure 3 ) can be attributed to the absence of a liquid B 2 O 3 layer due to the formation of a ternary oxide containing Al, B, and O, as observed from the HAADF–STEM–EDS and XRD analyses of the oxidized sample along with the study of the phase diagram of the Al 2 O 3 /B 2 O 3 mixture. 31 These ternary oxides take care of the limitation of molten B 2 O 3 by providing porous channels for oxidizers to trigger B oxidation. 17 The presence of ternary oxides reduces the clogging of B pores and aggregation of particles by molten B 2 O 3 .…”

Tribology and Anti-Ablation Properties of SiC-VN-MoS2/Ta Composite Coatings on Carbon/Carbon Composites from 25 to 800 °C

“…The CoF of BN was more than 0.25 under a contact load of 10 N, and a dry sliding speed of 1 mm/s [16]. The CoF of SiC sintered with Al was higher than 0.6 under dry sliding wear [17]. The CoF of CrN was more than 0.6 under dry sliding wear [18].…”

The Effects of Indium Additions on Tribological Behavior of Spark Plasma Sintering-Produced Graphene-Doped Alumina Matrix Composites for Self-Lubricating Applications

“…and the result was the self-lubricating ability of aluminum-metal matrix composites with added graphene [20]. Increasing demands for the lowest possible friction losses in various applications force research to be increasingly focused on self-lubricating materials [21,22], which are expected to provide excellent tribological properties under extreme conditions. In addition to methods of adding solid self-lubricating materials onto various functional surfaces (magnetron sputtering, laser cladding, thermal spraying, and vapor deposition techniques), powder metallurgy is a method of incorporating solid lubricants into a matrix [23][24][25][26][27][28][29][30][31][32][33][34].…”