Co-reporter:Zhi Liu, Kan Song, Bo Gao, Tian Tian, Haiou Yang, Xin Lin, Weidong Huang
Journal of Materials Science & Technology 2016 Volume 32(Issue 4) pp:320-325
Publication Date(Web):April 2016
DOI:10.1016/j.jmst.2015.11.017
Directionally solidified eutectic ceramics such as Al2O3/ZrO2 are promising structural materials for applications in harsh environment with an ultrahigh temperature. In this work, through adopting assistant heating laser 3D printing, Al2O3/ZrO2 eutectic samples were manufactured with suppressing the formation of cracks. The dependence of the average rod spacing (λav) on the scanning rate (V) follows a relation with λavV0.5 = 1 µm1.5 s–0.5. Typical eutectic microstructures, so-called complex regular, were analyzed with respect to its evolution with modulating the growth conditions. Formation mechanism of the solidification defect, shrinkage porosity, was discussed and the defect is found to be significantly suppressed by optimizing the solidification parameters. The maximum hardness and fracture toughness are measured to be 16.7 GPa and 4.5 MPa m1/2, respectively. The interplay between the propagation of cracks and the Al2O3/ZrO2 interface is discussed.
Co-reporter:Yicheng Cheng;Jiang Hu;Chunbao Zhang;Zhongyi Wang;Yulin Hao
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2013 Volume 101B( Issue 2) pp:287-294
Publication Date(Web):
DOI:10.1002/jbm.b.32838
Abstract
Ti-24Nb-4Zr-7.9Sn (TNZS) alloy is a newly developed β-titanium alloy considered suitable for dental implant applications due to its low elastic modulus and high strength. The aim of this study was to investigate the corrosion behavior of TNZS alloy through a static immersion test in various simulated physiological solutions, namely, artificial saliva, lactic acid solution, fluoridated saliva, and fluoridated acidified saliva for 7 days. The corrosion behavior of commercially pure titanium and Ti-6Al-4V alloy were also examined for comparison. The elemental release was measured with inductively coupled plasma mass spectroscopy, and the changes of alloy surface were observed with scanning electron microscopy (SEM). The test results showed that the quantity of each metal element released from TNZS alloy into fluoridated solutions was much higher than the solutions without fluoride ions. It was highest in fluoridated acidified saliva and lowest in artificial saliva (p < 0.01). The total elemental release from TNZS alloy was lower than commercially pure titanium and Ti-6Al-4V alloy in the same solution (p < 0.01). SEM micrographs indicated that TNZS alloy possessed better corrosion resistant performance. It can be concluded that fluoridated solutions have a negative influence on the corrosion behavior of TNZS alloy. Compared with commercially pure titanium and Ti-6Al-4V alloy, TNZS alloy demonstrates better corrosion resistance in various simulated physiological solutions, so it has greater potential for dental implant applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Co-reporter:Jiang Wu, Jian Zhou, Wen Zhao, Bo Gao
Materials Science and Engineering: C 2013 Volume 33(Issue 1) pp:140-144
Publication Date(Web):1 January 2013
DOI:10.1016/j.msec.2012.08.020
The purpose of this study was to compare the bonding characteristics of titanium porcelain Duceratin bonded to Ti–24Nb–4Zr–7.9Sn (TNZS) alloy and commercial pure titanium (cp Ti). The bond strengths between porcelain and TNZS were tested by a three-point flexural device. The same tests for the cp Ti were used as for the control. Coefficient of thermal expansion (CTE) of TNZS was evaluated with a push-rod dilatometer. Interfacial characterization was carried out by X-ray energy-dispersive spectrometry (EDS) analysis operating in line scan mode. Additionally, microstructure characterizations of TNZS and cp Ti after debonding fracture were analyzed by scanning electron microscope (SEM) and EDS. The porcelain bond strength of TNZS alloy was 31.51 MPa, showing a significant increase relatively to that of cp Ti (23.89 MPa) (P < 0.05). Mean CTE values of TNZS alloy was 9.51 × 10− 6/°C exceeding the porcelain by 0.81 × 10− 6/°C, attesting to a better mechanical performance. Interfacial characterization showed the mutual diffusion of Ti, Si, O and Sn along the TNZS–ceramic interface. Both SEM and EDS results revealed that fracture modes of TNZS specimens exhibited a mixed mode of cohesive and adhesive failures. The results demonstrated that TNZS could be a good alternative for the metal–ceramic restoration in the future.Highlights► Comparing to cp Ti, TNZS alloy showed a significant improvement in bond strength. ► We checked the coefficient of thermal expansion (CTE) of TNZS. ► The fracture mode of TNZS–porcelain showed a mixed cohesive and adhesive failure. ► TNZS could be a good alternative for the metal–ceramic restoration in the future.
Co-reporter:Yihan Liu;Zhongyi Wang;Xiaoming Zhao;Xin Lin
Lasers in Medical Science 2010 Volume 25( Issue 6) pp:799-804
Publication Date(Web):2010/11/01
DOI:10.1007/s10103-009-0690-3
The aim was to evaluate the mechanical properties and porcelain bonded strength of nickel–chromium (Ni–Cr) dental alloy fabricated by laser rapid forming (LRF). The tensile properties and porcelain bonded strengths of LRF Ni–Cr dental alloy were evaluated by tensile tests (five specimens per group) and three-point bending tests (ten specimens per group). The same tests for the cast Ni–Cr dental alloy were used as for the control. The microstructure and the bonding interface of the metal substrate to porcelain were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The tensile strength of LRF Ni–Cr dental alloy (840 MPa) was superior to that of the cast Ni–Cr alloy (670 MPa), but the ductility had decreased. The porcelain bonded strength of LRF Ni–Cr dental alloy was 44.7 MPa, which was also superior to that of the cast Ni–Cr dental alloy (41.6 MPa). According to analysis by Student’s t-test, the porcelain bonded strengths of the Ni–Cr dental alloy presented statistically significant differences between the groups of LRF and cast alloy (P < 0.05), but the porcelain bonded strengths were all above the acceptable value required by the International Organization for Standardization (ISO) standard 9693 (25 MPa). The coefficient of thermal expansion (CTE, mean value of five specimens) of LRF Ni–Cr dental alloy (14 × 10−6°C−1) was higher than that (13.7 × 10−6°C−1) of the cast Ni–Cr dental alloy. Both LRF and cast Ni–Cr dental alloy had positive Δα, not exceeding the maximum difference (1 × 10−6°C−1) in CTE. SEM and EDS results showed that all the specimens measured for porcelain bonded strength and prepared from the LRF and cast Ni–Cr alloy exhibited a mixed mode of cohesive and adhesive failure. Evaluation of the mechanical properties and porcelain bonded strengths of LRF Ni–Cr alloy revealed that both superior tensile and porcelain bonded properties can be obtained. With improvement of the technique, it is hoped that the LRF Ni–Cr dental alloy could be a good alternative to the conventional cast Ni–Cr dental alloy in the future.
Co-reporter:Jiang Wu;Hua Tan;Jing Chen;Chak-yin Tang
Lasers in Medical Science 2010 Volume 25( Issue 3) pp:309-315
Publication Date(Web):2010 May
DOI:10.1007/s10103-008-0603-x
This work attempted to integrate the technologies of computer-aided design and computer-aided manufacture (CAD/CAM) and laser rapid forming (LRF) for the fabrication of the titanium plate of a complete denture. By the combination of laser scan and reverse engineering software, the standard triangulation language (STL)-formatted denture base plate was finally designed and sliced into a sequence of numerical controlled codes. The titanium (Ti) complete denture plate was finally built, layer-by-layer, on the LRF system. To evaluate the quality of fit, a virtual adaptation test that measured and compared the profiles of the laser free formed denture plate and those of the edentulous plaster cast had been conducted, and the mean deviation was found to be 0.34 mm. After traditional dental finishing techniques, a complete denture with a Ti base plate was then made and judged to be acceptable. The CAD/CAM/LRF system is a potential candidate and a new platform for the design and manufacture of custom-made Ti denture plates and restorations.
Co-reporter:Jiang Wu;Zheng-Ming Liu;Xiang-Hui Zhao;Yang Gao;Jiang Hu
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2010 Volume 92B( Issue 2) pp:298-306
Publication Date(Web):
DOI:10.1002/jbm.b.31515
Abstract
Ti-24Nb-4Zr-7.9Sn (TNZS) is a newly developed β-titanium alloy with low modulus and it has been considered as good material for dental or orthopedic implant. The purpose of the current study is to evaluate the effect of micro-arc oxidation (MAO) treatment on the biological performance of TNZS surface. The phases, morphology and chemical composition of the MAO-treated surface were characterized by X-ray diffraction, energy dispersive spectroscope and scanning electron microscopy analysis respectively. Then we tested the biocompatibility by examining the cell morphology and viability of osteoblast cells growing on MAO-TNZS surface. The bone binding strength of the specimens was evaluated by removal torque test after implantation in rabbit tibiae for 6 weeks. Compared with the none-treated titanium and TNZS specimens, MAO treated TNZS specimens showed a significant increase (p<0.05) in hydrophilicity, roughness, cell viability and removal torque forces. In summary, MAO treatment helps to form a porous surface with a biologically active bone-like apatite layer on TNZS specimens, which may improve the biological response of MAO-TNZS implants. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
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