Ultra high temperature ceramic composite materials

Ultra-high temperature ceramics (UHTCs) are materials that have been demonstrated to withstand temperatures up to around 3000°C, thermal fluxes of ~17 MWm-2 and gas velocities of around Mach 0.6. Thus, they offer potential for use in applications such as leading edges and engine parts for hypervelocity vehicles. Under the Domain 8 of the MCM-ITP (Materials and Components for Missiles – Innovation and Technology Partnership) programme, research has been carried out investigating UHTC composites consisting of carbon fibre (Cf) preforms impregnated with HfB2 powders. Whilst the initial impregnation route resulted in preforms with high and uniform powder loadings, this was not true for large samples. As a result, the mechanical properties showed a high degree of scatter. Nevertheless, samples with higher final densities showed higher strengths. Thus a new impregnation route has been developed that results in both higher and more homogeneous powder loading. This has led to higher strengths and even greater temperature and ablation resistance with the only penalty being an increase in component mass. A prototype jet vane has been successfully produced

Dietary intakes in infertile women a pilot study

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Synthesis and characterization of fully bio-based unsaturated polyester resins

The sustainable tomorrow for future generations lies with the present industrial development toward the proper utilization of various bio-based products. For a transition to a higher level of sustainability, it is necessary to form a new platform for advanced technology products. This paper reports the development of new fully bio-based unsaturated polyesters resins (UPRs). A series of prepolymers were synthesized by varying saturated diacids (oxalic, succinic and adipic acid), itaconic acid and 1,2-propandiol. Dimethyl itaconate was used as a reactive diluent (RD) in amounts of 30, 35 and 40 wt%. Rheological measurements showed that the obtained resins possessed viscosities (234-2226 mPa s) amenable to a variety of liquid molding techniques. The impact of composition variables-prepolymer structure and amount of RD-on the chemical, mechanical and thermal properties of the thermosets was examined by DMA, TA and tensile measurements and was discussed in detail. The tensile properties (37-52 MPa), glass transition temperature (60-97 A degrees C) and coefficient of thermal expansion (71-168 10(-6) A degrees C-1) of the cured resins were in the desired range for UPRs. This investigation showed that UPRs based on itaconic acid can be tailored during synthesis of the prepolymer to meet the needs of different property profiles