In this study, we prepared hydroxyapatite ceramics at 300℃ by hydrothermal hot pressing using octacalcium phosphate as the starting material. The phase and microstructure of the solidified body were determined by X-ray diffraction and scanning electron microscopy. The Vickers's hardness, bending strength and fracture toughness were measured by micro-hardness test and 3-point-bending test, respectively. The results show that c axis of hydroxyapatite crystal points to the direction normal to the load that applied during hydrothermal hot pressing. The grains are sheet and stack up to a clamshell structure along the direction the load direction. According to the microstructure, the mechanical properties of the HAp ceramics appear strong anisotropy. The bending strength and fracture toughness tested on the side normal to the load direction reach 39.6MPa and 1.34MPam^<1/2>, respectively.

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Engine experiments have been conducted on a gas fueled SI engine. The engine was fueled with natural gas and mixtures of natural gas and hydrogen containing producer gas in order to examine the effect of addition of the producer gas on the combustion process and the engine-out emissions. The in-cylinder HC concentration at the vicinity of the spark plug and the UHC concentration in the exhaust port near the exhaust valve was measured using FFID. The experiments showed that addition of producer gas had reducing effect on the UHC emission at conditions leaner than λ=1.40. The manifold FFID measurements showed that the reduction in the total engine-out UHC emission by addition of producer gas is mainly caused by a reduction in cyclic variations and only to a minor extent by a general lower UHC level.

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