This paper presents a study of the tribological properties of three-dimensional (3-D) braided carbon/Kevlar/epoxy hybrid composites. Their specific wear rate and the coefficient of friction were examined as a function of operating conditions (load and sliding distance) under dry and lubricated conditions. In addition, the 3-D braided hybrid composites with varying carbon to Kevlar fiber volume ratio were tested to assess hybrid effects. It was found that the friction and wear rate decreased with sliding distance and then leveled off under dry and lubricated conditions. Different changing patterns with normal load were observed under two different sliding conditions. Furthermore, it was noted that negative hybrid effects on the wear resistance and the friction coefficient were identified for the current 3-D braided hybrid system. The composite with a carbon to Kevlar ratio of 3:2 was found to have the least wear and friction among all 3-D braided hybrid composites studied. Worn surfaces were observed by scanning electron microscope (SEM) and wear mechanisms were discussed in this study.

Hydroxyapatite (HAp) and bacterial cellulose (BC) are both excellent materials for use in biomaterial areas. The former has outstanding osteoconductivity and bioactivity and the latter is a high-strength nano-fibrous and extensively used biomaterial. In this work, the HAp/BC nanocomposites with a 3-dimensional (3-D) network were synthesized via a biological route by soaking both phosphorylated and unphosphorylated BCs in 1.5 simulated body fluid (SBF). Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) were employed to characterize the HAp/BC nanocomposites. SEM observations demonstrated that HAp crystals were uniformly formed on the phosphorylated BC fibers after soaking in 1.5 SBF whereas little Hap was observed on individual unphosphorylated BC fibers. Our experimental results suggested that the unphosphorylated BC did not induce Hap growth and that phosphorylation effectively triggered HAp formation on BC. Mechanisms were proposed for the explanation of the experimental observations. XRD and FTIR results revealed that the HAp crystals formed on the phosphorylated BC fibers were carbonate-containing with nanosized crystallites and crystallinities less than 1%. These structural features were close to those of biological apatites.

Short, unidirectional and laminated hybrid composites have been extensively investigated. However, very limited work has been conducted on three-dimensional (3-D) braided hybrid composites. In this work, 3-D braided carbon and Kevlar fibres were hybridized to reinforce a bismaleimide (BMI) resin. The purpose of this paper was to investigate the effect of carbon to Kevlar ratio on such mechanical properties as load–displacement behaviour, flexural strength and modulus, shear strength, and impact properties. The effect of surface treatment of hybrid fabrics on the flexural properties was also determined. Experimental results showed that the flexural strength and modulus of the 3-D braided carbon/Kevlar/BMI composites increased with relative carbon fibre loading up to a carbon to Kevlar ratio of 3:2 and then dropped. Positive hybrid effects were observed for both flexural strength and modulus. The results presented in this work proved that hybridization with certain amount of ductile Kevlar fibre markedly promoted the shear strength, impact energy absorption characteristics and damage tolerance of the all-carbon composite, which is of importance for the 3-D braided composites to be used in bone fixations. Fracture surfaces and microstructures of various 3-D braided hybrid composites were analyzed to interpret the experimental findings.

A combined procedure of sol-gel and microwave-assisted emulsion polymerization has been developed to prepare TiO2/polystyrene core-shell nanospheres with nano-scale TiO2 core and smooth and well-defined polystyrene shell. The core-shell structure and morphology were examined by TEM. The diameter and its distribution of the nanospheres were measured by dynamic light scattering. The nanospheres were characterized with Fourier transform infrared spectroscopy (FTIR). It is found that the diameter and its distribution of the TiO2/polystyrene core-shell nanospheres can be regulated by the concentration of styrene monomer in the emulsion solution.

Orthotic devices have been commonly made from plastics like polypropylene. However, insufficient mechanical properties, labour intensive preparation process, long client’s visiting times urge us to seek an alternative. An orthotic device made from a light-curable composite material is expected to overcome the aforementioned shortcomings by allowing the shaping and hardening of the orthosis to be performed during one fitting directly on the patient. This paper examines the mechanical properties of the composite material made with a 2.5-dimensional (2.5-D) woven fabric and a custom light-curable resin designed specifically for orthotic applications. A corresponding 2-dimensional (2-D) composite was also made for comparison purpose. Static (flexural strength and modulus) and dynamic (impact and fatigue) mechanical properties of the 2.5-D and 2-D composites were investigated. It was found that both 2.5-D and 2-D composites exhibited much higher flexural strength and modulus than polypropylene. In addition, they were non-brittle in nature. Though inferior to the 2-D composite in static flexural properties, the 2.5-D composite was superior to the corresponding 2-D composite in terms of impact and fatigue properties. Other comparisons between the 2.5-D and 2-D composites were also made and scanning electron microscopy (SEM) observation was conducted in this work.

Implant related infections remain a concern in modern surgery. Surface modification is an effective way to reduce the occurrence of these complications. Of various techniques, ion implantation shows promise. In the present work, silver and copper were ion implanted separately, into three typical medical metals, namely 317L stainless steel, titanium, and Ti-Al-Nb by a MEVVA ion source machine at various ion doses. The objective of this study was to determine the influence of silver and copper ion implantation on antibacterial performance and wear and corrosion resistance of the three materials. Antibacterial activity of silver-and copperimplanted samples against Staphylococcus aureus were assessed by the plate-counting method. The results show that silver and copper implantation improves the antibacterial rate and wear performance of all the three metals studied. It is also found that silver ion implantation does not change the corrosion resistance while the corrosion resistance of copper-implanted samples shows a significant decline. In conclusion, silver ion implantation is favorable to copper ion implantation for increasing the antibacterial nature of these three metals.

This paper describes the biosynthesis of a novel collagen-bacterial cellulose (COL/BC) composite by adding collagen to the culture medium of Acetobacter xylinum. The morphology of COL/BC composite was observed by SEM and TEM and compared with pristine BC. The composite was further characterized by FTIR and XRD. It is found that the structure of BC network changes when collagen is present in the nutrient medium. Further work is underway to gain insights into the mechanisms governing the experimental phenomena.

The effect of copper ion implantation on the antibacterial activity, wear performance and corrosion resistance of medical metals including 317 L of stainless steels, pure titanium, and Ti-Al-Nb alloy was studied in this work. The specimens were implanted with copper ions using a MEVVA source ion implanter with ion doses ranging from 0.5×10 17 to 4×10 17 ions/cm2 at an energy of 80 keV. The antibacterial effect, wear rate, and inflexion potential were measured as a function of ion dose. The results obtained indicate that copper ion implantation improves the antibacterial effect and wear behaviour for all the three medical materials studied. However, corrosion resistance decreases after ion implantation of copper. Experimental results indicate that the antibacterial property and corrosion resistance should be balanced for medical titanium materials. The marked deteriorated corrosion resistance of 317 L suggests that copper implantation may not be an effective method of improving its antibacterial activity.

A Si5C3 type silicon carbon has been prepared via carbon ion implantation into silicon substrate using a MEVVA ion source. Carbon ions were implanted into silicon substrate at a fluence of 5×1017 ions/cm2 and then the as-implanted samples were annealed at 1250℃ for 2h. The thermal annealing produced a silicon carbide layer on the surface of silicon substrate. The results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirm the existence of Si5C3, rather than SiC. The results of Fourier transform infrared reflection (FTIR) and Raman spectroscopy analyses show that the Si–C vibration frequency in crystalline Si5C3 is slightly less than that in crystalline β-SiC.

Plasma polymerization gains increasing interest for the deposition of films with functional properties suitable for a wide range of modern applications on account of its advantageous features. In this study, carbon dioxide (CO2) was chosen as carrier gas at flow rates of 30 and 60 sccm, respectively and styrene vapor was used as the monomer to prepare polystyrene films on glass substrates. The structure and composition of the plasma polymerized films were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and compared with the film prepared by conventional thermal polymerization. The morphology information of the films was provided by optical microscopy. XPS and FT-IR results reveal that chemical composition of the plasma polymerized films is different from that of the thermal polymerized film and that oxygen content in the plasma polymerized films increases with the flow rate of CO2. Furthermore, the presence of oxygen-containing groups on the surface of plasma polymerized polystyrene films is confirmed. It is also found that the composition and morphology of the plasma polymerized films are controlled by the flow rate of CO2.