Selected Abstracts of Thermal Spray Literature
- PDF / 336,855 Bytes
- 13 Pages / 593.972 x 792 pts Page_size
- 90 Downloads / 174 Views
Selected Abstracts of Thermal Spray Literature Reprinted with permission from Elsevier Engineering Information, Inc., Hoboken, NJ
Coatings for Biological Systems Effects of technological parameters on the microstructure of laser remelted hydroxyapatite (HA) coatings. In this paper, the influence of different laser power and scanning speed on the microstructure of laser remelted as-sprayed hydroxyapatite (HA) coatings was studied and the optimum technological parameters were obtained. The morphologies, elements, and phase analysis of both sprayed and remelted coatings were examined by means of electron probe microanalysis, x-ray diffraction, and so on. The results show that the plasma sprayed coatings could be improved by laser remelting, and the optimum technological parameters are that the laser power is 600 W and the scanning speed is 11.2 mm/s. In the technological condition, the remelted coating that has compact columnar and cellular dendritic crystal consists of HA, a-TCP, CaO, and TiO2 phases, and the Ca/P ratio of the coating is the most approximate to that of HA. When increasing the laser power and slowing the scanning speed, the structure of the coating will become much coarser and the Ca/P ratio will deviate more from that of HA. On the contrary, if the laser power is reduced and the scanning speed is accelerated, the influence of technological parameters of laser remelting on the sprayed coating will be weakened. Keywords: dendritic crystal, electron probe microanalysis, hydroxyapatite, laser remelted hydroxyapatite (HA) coatings, lasers, optimum technological parameters, plasma spraying, remelting, scanning, scanning speed, x-ray diffraction C. Chen, D. Wang, Q. Bao, and T. Lei, School of Materials Science and Engineering, Shandong University, Jinan 250061, China. Cited: J. Phys. D: Appl. Phys., 2006, March 21, 39(6), p 1169-1173. ISSN 0022-3727. Nanostructural bioactive gradient coating fabricated by computercontrolled plasma spraying technology. The poor mechanical property of hydroxyapatite was the major problem for load bearing and implant coating in clinical applications. To overcome this weakness, a bioactive gradient coating with a special design composition of hydroxyapatite (HA), ZrO2, Ti, bioglass was developed. This 120 lm coating with an upper layer of 30-50 lm porous HA produced by computer-controlled plasma spraying that maintained the energy level of the plasma to ensure proper melting of powder. The crystal size of the coating was 18.6 to 26.2 nm. Transformation of t-ZrO2 to m-ZrO2 reduced the thermal stress that weakened the coating and lowered interfacial strength of the coating and metal substrate. Thermal stress of sprayed coating was 16.4 MPa, which was much smaller than the sample without thermal treatment of 67.1 MPa. Interfacial strength between the coating and metal substrate was 53 MPa, which is much higher than conventional hydroxyapatite coating. Based on XRD analysis crystallinity of HA approached 98%. Therefore, hightemperature treatment improved long-term stability of the c
Data Loading...
