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Open Access Research Article Issue
Comparative study of tribological properties of insulated and conductive polyimide composites
Friction 2020, 8 (3): 507-516
Published: 01 April 2019
Downloads:13

Insulated polyimide (PI) composites filled with short glass fibers (SGF), polytetrafluoroethylene (PTFE), SiO2, and polyphenylene (PPL) are specially designed, prepared, and the tribological properties are systematically investigated with references to the special requirements for frictional materials used in ultrasonic motors. The hardness and thermal decomposition temperature of the insulated PI composites are comparable to that of conductive PI composites. However, these insulated materials present excellent friction and wear performance, especially under high loads and speeds. Scanning electron microscopy (SEM) analysis of the worn surface indicates that adhesive and fatigue wear dominate the wear mechanisms.

Open Access Research Article Issue
Microstructure and piezoelectric properties of K5.70Li4.07Nb10.23O30-added K0.5Na0.5NbO3 ceramics
Journal of Advanced Ceramics 2014, 3 (2): 147-154
Published: 01 June 2014
Downloads:22

Lead-free piezoelectric ceramics K0.5Na0.5NbO3xmol%K5.70Li4.07Nb10.23O30 (x = 0–2.5, KNN–xmol%KLN) were prepared by conventional sintering technique. The phase structure and electrical properties of KNN ceramics were investigated as a function of KLN concentration. The results showed that small amount of KLN introduced into the lattice formed a single phase perovskite structure. The KLN modification lowered the phase transition temperature of orthorhombic–tetragonal (TO–T) and increased the Curie temperature (TC). Some abnormal coarse grains were formed in a matrix when the content of KLN was relatively low (1 mol%). However, normally grown grains were only observed when the sintering aid content was increased to 2 mol%. Proper content of KLN decreased the amount of defects, thus the remanent polarization increased and the coercive field decreased markedly, and the sinterability of the KNN ceramics was simultaneously improved with significant increase of piezoelectric properties.

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