| 1 | Formation of TiN Grid on NiTi by Laser Gas Nitriding for Improving Wear Resistance in Hanks' Solution显示文摘Laser gas nitriding(LGN)is a common surface modi?cation method to enhance the wear resistance of titanium(Ti)alloys,which are known to have poor tribological properties.In the present study,a titanium nitride(TiN)grid network was fabricated on the surface of nickel titanium(NiTi)by LGN.The laser processing parameters were selected to achieve nitriding without surface melting and hence to maintain a smooth surface?nish.The characteristics of the grid-nitrided samples were investigated by scanningelectron microscopy,X-ray diffractometry,optical microscopy,2-D pro?lometry,contact angle measurements and nanoindentation.The wear resistance of the nitrided samples was evaluated using reciprocating wear test against ultra-high-molecular-weight polyethylene(UHMWPE)in Hanks’solution.The results indicate that the wear rates of the grid-nitrided samples and the UHMWPE counter-body in the wear pair are both signi?cantly reduced.The decrease in wear rates can be attributed to the combination of a hard TiN grid and a soft NiTi substrate.In Hanks’solution,the higher hydrophilicity of the nitrided samples also contributes to the better performance in wear test against hydrophobic UHMWPE. | C.H.Ng O.K.Chan H.C.Man | 2016 | Journal of Materials Science & Technology2016，32，5： | 3 |
| 2 | Incorporating geotechnical and geophysical investigations for underground obstruction detection:A case study显示文摘Determining the location and boundary of underground obstructions and/or anomalies is a common problem and often a great chal-lenge for tunneling and underground construction.In this study,geotechnical investigations(penetration tests and borehole drilling/sam-pling)and geophysical investigations(surface wave method and cross-hole seismic method)were conducted with the aim of identifying the location and boundary of rock obstructions in Changi East,Singapore.The surface wave method is frequently used in the sites with lateral homogeneity in previous studies,but its application in the sites with rock obstructions is rare.The experimental results of this study indicate that the surface wave method is also able to determine the upper surface of rock obstructions,but difficult to identify the lateral and bottom boundaries of rock obstructions.To improve the precision of detection,the full waveform inversion(FWI)method was used to process the data from the cross-hole seismic survey.The results indicate that the inversion precision of P-wave is higher than that of S-wave.The horizontal and vertical ranges of rock obstructions in the P-wave inversion results are 14–26 m and 7.5–11.0 m respectively,roughly consistent with the results of penetration tests(about 15–25 m)and borehole log(8.85–10.80 m).This result proves that the sequential application of first-arrival time analysis and FWI can effectively delineate the boundary of rock obstruc-tions.Finally,the results of various detection methods were analyzed and compared in this study.Considering the advantages of various methods,we propose a cost-effective and high-precision workflow containing both geotechnical and geophysical investigations. | Yaohui Liu Yannick C.H.Ng Yunhuo Zhang Ping Yang Taeseo Ku | 2023 | Underground Space2023，，4： | 0 |
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