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Full-Text Articles in Engineering

An Analysis On The Microstructure Of Electrodeposited Zro 2 Ni Functionally Graded Materials, Chengjun Quan, Xinghua Xiang, Jingchuan Zhu, Zhongda Yin May 1997

An Analysis On The Microstructure Of Electrodeposited Zro 2 Ni Functionally Graded Materials, Chengjun Quan, Xinghua Xiang, Jingchuan Zhu, Zhongda Yin

Journal of Electrochemistry

The electrodeposited ZrO 2 Ni functionally graded coating was fabricated by controlling the ZrO 2 concentration in the bath, and the microstructure was analyzed by X Ray Diffraction (XRD) and Electron Probe Microanalysis (EPMA). The results show that the functionally graded coating has excellent compositional gradient distribution from the substrate to the surface. The content of ZrO 2 is up to 14.4 vol% in the surface layer and the coating consists of the t ZrO 2, m ZrO 2 and Ni phases. Owing to the ZrO 2 particles pressed by Ni atoms during electrodepositing, t→m transformation has occurred.


Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo Jan 1997

Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo

Cells and Materials

Four high-palladium dental alloys were cast, quenched following solidification, and heat treated at temperatures ranging from 200° to 1,800°F. The Vickers hardness of each alloy was measured, and microstructural changes were studied by scanning electron microscopy (SEM). Phase transformations were investigated by thermomechanical analysis (TMA). Heat treatment at 1,600° and 1,800°F significantly decreased the hardness of one Pd-Cu-Ga alloy, compared to the as-cast condition, as did heat treatment at 1,800°F for the other Pd-Cu-Ga alloy and one Pd-Ga alloy, and yielded fine-grained microstructures of the palladium solid solution. There were generally no significant changes in the hardness of the other …


Mechanism For Formation Of Lamellar Constituents In Grain-Refined Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, John C. Mitchell, Stanley G. Vermilyea Jan 1997

Mechanism For Formation Of Lamellar Constituents In Grain-Refined Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, John C. Mitchell, Stanley G. Vermilyea

Cells and Materials

Grain-refined Pd-Cu-Ga dental alloys solidify with a lamellar microstructural constituent that affects a variety of clinically relevant properties. While formation of this constituent has been attributed to eutectic solidification, an alternative mechanism of discontinuous precipitation has been proposed. Using a representative grain-refined Pd-Cu-Ga dental alloy, casting procedures involving two different rates of solidification were used: (a) A standard thin-walled coping configuration for a metal-ceramic restoration was cast into a room temperature mold, followed by rapid quenching into an ice-water mixture. (b) A thin plate specimen was cast into a standard elevated-temperature mold, with the same subsequent rapid quenching procedure. Neither …