Tool steels serve a large range of applications including hot and cold workings of metals and injection mouldings of plastics or light alloys. The high speed steels (HSS) are specifically used as cutting tools and wear parts because it has high strength, wear resistance and hardness along with appreciable toughness and fatigue resistance. From the view of HSS microstructure, it can be described as metallic matrix composites formed by a ferrous with a dispersion of hard and wear resistant carbides. The experimental specimens were manufactured using the PIM with T42 powders (50~80 vol.%) and polymer (20~50 vol.%). The green parts were debinded in n-hexane solution at for 8 hours and thermal debinded at an mixed gas atmosphere for 8 hours. Specimens were sintered in high vacuum ( Torr) and various temperatures.

In order to investigate the microstructure and mechanical properties of WC-10 wt% Co insert tool alloy fabricated by PIM (Powder Injection Molding) process, the feedstock of WC-10 wt% and wax used as a kind of binder were mixed together by two blade mixer. After injection molding, the debinding process was carried out by two-steps. First, solvent extraction, in which the binder was eliminated by putting the specimen into normal hexane for 24 hrs at , and subsequently thermal debinding which was conducted at and for 6 hrs in the mixed gas of , respectively. Meantime, in order to compensate the decarburization due to hydrogen, 1.2~1.8% of carbon was added to ensure the integrity of the phase. Finally, the specimens were sintered in vacuum under different temperatures, and the relative density of 99.8% and hardness of 2100 Hv can be achieved when sintered at , even the TRS is lower than the conventional sintering process.

Pure WC powders which does not include a binder phase were consolidated by spark plasma sintering (SPS) process at 1600~185 for 0~30 min under 50 MPa. Microstructure alid mechanical properties of binderless WC prepared by SPS were investigated. With increasing sintering temperature, sintered density and Vickers hardness of binderless WC increased. The fracture toughness of binderless WC was 7~15 MPa depending on the sintered density and decreased with increasing the Vickers hardness. It is found that the binderless WC prepared by SPS at 175 for 10 min under 50 MPa showed nearly full densification with fine-grained structure and revealed excellent mechanical properties of high hardness (~HV 2400) and considerably high fracture toughness (~7 MPa ).

This study evaluated the effect of organic fertilizer on the yield of sesame and the movement of nitrogen and carbon in soil under mulching cultivation. The seven fertilizer treatments investigated are as follows: 1) 8-4-9 kg N-P2O5-K2O 10a-1-control, 2) 80% of control treatment N from mixed expeller cake (MEC)-MEC 80%, 3) 100% of control treatment N from MEC-MEC 100%, 4) 80% of control treatment N from mixed organic fertilizer (MOF)MOF 80%, 5) 100% of control treatment N from MOF-MOF 100%, 6) 80% of control treatment N from latex coated urea complex fertilizer (LCU)-LCU 80%, and 7) no nitrogen. The soil mineral N available in the applied organic MEC and MOF fertilizers was less than the available N in the applied urea fertilizer during the early growth stage of sesame but the amount was observed to increase with time. The concentration of nitrate-N in leached solution 35 days after application was highest at 75 mg l-1 in the control, followed in descending order by MEC 100%, MOF 100%, LCU 80%, MOF 80% and MEC 80%. The concentration of nitrate-N in the leachate in all treatments was observed to rapidly decrease 45 days after fertilizer application and recorded at less than 20 mg l-1 65 days after application. The concentration of dissolved organic carbon in the leached solution and organic carbon in the soil of the organic fertilizer plots was higher than in the urea- and LCU-fertilized plots during the whole growing period. The yields of sesame applied with MEC and MOF organic fertilizers were 2 to 7% higher than those fertilized with urea. The amount of retained mineral N or organic carbon in the soil is higher in the LCU and organic fertilizer plots than in the urea-fertilized treatments, which resulted in the reduction of nitrate leaching, increasing N efficiency and sesame yield.

This study was conducted to evaluate the effect of slow release fertilizers (SRF), crotonylidene diurea (CDU) and latex coated urea (LCU), on nitrogen (N) use efficiency (NUE) and nitrate-N leaching in a silty clay loam soil under polyethylene film mulching (PFM) for sesame cultivation. In PFM plot, concentrations of NO3-N and NH4-N in SRF applied soils were less than that in the urea plot during the whole growing period. However, NO3-N and NH4-N in all the non-mulched plots (NM) were not significantly different. Urea-N in soil treated with SRF was higher than urea plot until 50 days after application and was comparable in all the treatments after 50 days. NO3-N concentrations in leached solution in 21 days after urea fertilization in PFM and NM were 26 mg L-1 and 83 mg L-1 , respectively. However, NO3-N in leached solution at applied CDU and LCU was less than that of urea similar to nitrate concentration in soil. NO3-N in leached solution in applied CDU and LCU in 44 days after application was about 25% lower than that urea plot and PFM, while the NO3-N concentration of CDU and LCU treatment in NM did not changed. Application of SRF increased the yield of sesame and N recovery compared to urea and there was a little difference between SRF and N levels. In conclusion, application of 80% N level with SRF increased N recovery and reduced nitrate leaching without reduction of yields compared with urea application.