Papers by Author: L. Yang

Abstract: A nanometer profilometer in which the measuring force can be controlled is proposed. The key part is the nanometer profiling core, which consists of a voice coil motor with a short and movable voice coil and an inductive transducer. According to the A/D value of the transducer signal, the measuring force can be adjusted to approximately µN level by use of a PID control algorithm. The advantages of contact type and non-contact type profilometer are possessed by the proposed instrument.

Abstract: Plasma-sprayed hydroxyapatite coating on metal substrate was prepared. Two kind of post-treatment methods were been applied to the coating, treatment in air at 650°C for 30 min and treatment in water vapor at 125°C with a pressure of 0.15MPa for 6 hours. XRD showed that the HA nanocrystals increased after water vapor treatment. The interfacial tensile bond strength between HA and substrate was 45.0±1.82MPa, 39.1±1.27MPa and 30.3±1.61MPa for as-received coatings, water vapor treated coatings and heated in air coatings, respectively. 3 months after implantation in dogs limbs, the push-out strength between implants and bone was 11.27±2.71MPa, 11.63±3.11MPa, 23.92± 2.01MPa and 18.8± 1.82MPa for pure Ti implants, as-received coating implants, water vapor treated implants and heated in air implants, respectively. The results showed that the post-water vapor treated HA coating have better mechanical behavior in vitro and in vivo

Abstract: The three different structures of titanium oxide film were prepared: (1) The commercial pure titanium was treated with heating in air at 700°C for half hour and gotten a dense rutile film on titanium (HS Samples); (2) The commercial pure titanium was treated by chemically treating and gotten a layer of amorphous titania gel on the Ti surface (TS Samples); (3) After chemically treating, the samples were heated in air at 700 °C for half hour, and gotten nano-particles coalesced microporous titanium oxide (rutile) film on titanium surface (XS sample). The dense rutile and amorphous titania gel did not induce apatite formation on their surfaces in SBF solution for 48 hours, whereas the nano-particles coalesced microporous rutile structure induced apatite formation on their surfaces. Mechanical test and histological examination were investigated after the samples implanted in dogs limbs for 3 months. The results of push-out test are 12.96, 29.48 and 35.83 MPa respectively for HS, TS and XS sample. Histological results showed that TS sample and XS sample contacted the bone directly, without any intervening fibrous tissue, and there was a fibrous tissue layer between the bone and HS samples.

Abstract: Plasma-sprayed hydroxyapatite coating on metal substrate has been prepared, two kinds of post-treatment methods have been used: (1) Heating in air at 650°C for 30 min, (2) Heating in water vapor at 125°C, 0.15Mpa for 6 hours. XRD showed that the nanocrystals of HA coating increased after water vapor treated. The interfacial tensiles strength between HA and the substrate were 45.0±1.82MPa, 39.1±1.27MPa and 30.3±1.61MPa for as-received coatings, water vapor treated coatings and heated in air coatings respectively. After 3 months implant in dogs limbs, the push-out strength between implants and bone were 11.27±2.71 MPa, 11.63±3.11MPa, 23.92± 2.01MPa and 18.8±1.82 MPa for pure Ti implants, as-received coating implants, water vapor treated implants and heated in air implants respectively. The results showed that the water vapor post treated HA coating have better mechanical behavior in vitro and in vivo.