Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects....Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behav- ior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via con. tinuous extrusion by carefully controlling the viscosity of binder.展开更多
CMA72 bonded Al2 O3 - MgO castable is promising for application of steel ladle wall, because of unique combination of thermo-mechanical properties, slag corro- sion resistance and cost benefit. In these castables, mi-...CMA72 bonded Al2 O3 - MgO castable is promising for application of steel ladle wall, because of unique combination of thermo-mechanical properties, slag corro- sion resistance and cost benefit. In these castables, mi- crosilica can be introduced to counterbalance the expan- sion generated by spinel formation. In this paper, the of microsilica dosage on properties of eastables was evaluated. Expansion, expressed by the permanent linear change （PLC）, is highly dependent on the dosage of microsilica. Unexpected expansion occurs when the dos- age of microsilica is too low due to dominant effect of spinel and CA6 formation. Too high dosage results in sintering shrinkage, which is related to amount of liquid phase generated by microsilica addition. In addition, HMOR declines dramatically with increasing microsilica dosage. Considering the balance between expansion con- trol and hot property retention, 1.0 mass% of microsili- ca is recommended for the castable containing 4 mass% of magnesia.展开更多
The manufacturing techniques of magnesia-carbon bricks in China have been documented from raw materials,production(process and facilities)to performance and wear issues in the ladle.Magnesia-carbon bricks made of ordi...The manufacturing techniques of magnesia-carbon bricks in China have been documented from raw materials,production(process and facilities)to performance and wear issues in the ladle.Magnesia-carbon bricks made of ordinary fused magnesia is the prevailing material used in the slagline of the ladle,but its service life is substantially lower than the bricks based on large-periclase-crystal fused magnesia.In two types of fused magnesia,the average values of periclase crystal size are in double for their difference.It is suggested that large-periclase-crystal fused magnesia should be used for manufacturing magnesia-carbon bricks for the slagline of the ladle by abandoning ordinary fused magnesia,in order to have a prolonged service life,increase the availability of the ladle and reduce the number of downtimes of the ladle.Free phenol in resin produced in China should be as low as that of resin made in Europe,to improve production environment and reduce smoke emission during the ladle preheating.There are large spaces to promote the productivity of magnesia-carbon bricks in China,with high intensity mixers and hydraulic presses.Expansion controlled magnesia-carbon bricks in the ladle depend on the optimized combination of sintered magnesia,Carbores and antioxidants as the matrix,to minimize the premature wear of vertical cracks and joint opening formed in the ladle lining.展开更多
The residual expansion of in-situ spinel formation in using of alumina-magnesia-carbon(AMC)bricks monolizes the lining of steel-making ladles with the closure of their joints,which has been an effective solution avoid...The residual expansion of in-situ spinel formation in using of alumina-magnesia-carbon(AMC)bricks monolizes the lining of steel-making ladles with the closure of their joints,which has been an effective solution avoiding washing out of the joints in ladle lining by the reduction of the penetration of liquid slag and molten steel.Alumina-magnesiacarbon refractories are overall reviewed,in terms of major raw materials,thermal evolution,corrosion and oxidation,and thermomechanical behavior,as well as type,addition and fraction of magnesia used.General commercial products contain 5%-10%MgO and 5%-10%C with a certain amount of metallic aluminum powder,which is believed to facilitate spinel formation at early stage of heating-up,although high magnesia containing AMC bricks are studied and used sometimes.With low ratio of Al_(2)O_(3)/C=12.9 and the carbon content of 6.4%C,AMC brick exhibits the highest corrosion resistance.It is important to determine the type,addition and fraction of magnesia used in AMC refractories for demonstrating high corrosion resistance and superior thermomechanical behavior.展开更多
文摘目的探讨治疗前胃癌患者^(18)F-FDG PET/CT显像特征,并分析影响胃癌原发灶最大标准摄取值(maximum standardized uptake value,SUVmax)的相关因素。方法选取并分析2017年1月~2019年12月经病理学证实的70例胃癌患者临床资料,所有患者均于治疗前在本院行PET/CT全身显像,显像结果采用半定量分析及视觉分析。不同病理分型、性别、年龄、是否淋巴结转移、是否脏器转移组间原发灶SUVmax值比较采用t检验;不同原发灶部位组间SUVmax值比较采用方差分析;原发灶最大厚度值与原发灶SUVmax值相关性采用Pearson相关分析。结果70例患者中66例原发灶18氟-氟代脱氧葡萄糖(^(18)F-2-fluro-D-deoxy-glucose,^(18)F-FDG)显像阳性,灵敏度94.3%,SUVmax9.6±4.9;PET显像灵敏度肠型胃癌高于非肠型胃癌〔33/33(100%)vs 27/31(87.1%)〕、非粘液腺癌高于粘液腺癌〔54/55(98.2%)vs 12/15(80.0%)〕。PET/CT对胃癌患者区域淋巴结转移诊断敏感性、特异性、准确性、阳性预测值、阴性预测值分别为86.7%、50.0%、76.2%、81.3%、60.0%;PET/CT提示23例患者存在脏器转移,以肝转移最常见。对各组间原发灶SUVmax值比较:肠型胃癌高于非肠型胃癌(12.2±6.3 vs 7.9±4.1,P=0.008)、非粘液腺癌高于粘液腺癌(12.9±7.1 vs 5.7±2.0,P=0.001)、伴脏器转移高于无脏器转移(13.1±7.5 vs 7.4±2.0,P=0.016);不同性别、年龄、是否淋巴结转移、原发灶部位组间差异无统计学意义(P>0.05)。病灶最大厚度值2.3±1.4与原发灶SUVmax值无相关(r=0.075,P>0.05)。结论PET/CT检查在胃癌原发灶诊断及淋巴结、脏器转移探查中具有重要价值,病理分型、脏器转移是影响原发灶SUVmax值的相关因素。
文摘Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behav- ior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via con. tinuous extrusion by carefully controlling the viscosity of binder.
文摘CMA72 bonded Al2 O3 - MgO castable is promising for application of steel ladle wall, because of unique combination of thermo-mechanical properties, slag corro- sion resistance and cost benefit. In these castables, mi- crosilica can be introduced to counterbalance the expan- sion generated by spinel formation. In this paper, the of microsilica dosage on properties of eastables was evaluated. Expansion, expressed by the permanent linear change （PLC）, is highly dependent on the dosage of microsilica. Unexpected expansion occurs when the dos- age of microsilica is too low due to dominant effect of spinel and CA6 formation. Too high dosage results in sintering shrinkage, which is related to amount of liquid phase generated by microsilica addition. In addition, HMOR declines dramatically with increasing microsilica dosage. Considering the balance between expansion con- trol and hot property retention, 1.0 mass% of microsili- ca is recommended for the castable containing 4 mass% of magnesia.
文摘The manufacturing techniques of magnesia-carbon bricks in China have been documented from raw materials,production(process and facilities)to performance and wear issues in the ladle.Magnesia-carbon bricks made of ordinary fused magnesia is the prevailing material used in the slagline of the ladle,but its service life is substantially lower than the bricks based on large-periclase-crystal fused magnesia.In two types of fused magnesia,the average values of periclase crystal size are in double for their difference.It is suggested that large-periclase-crystal fused magnesia should be used for manufacturing magnesia-carbon bricks for the slagline of the ladle by abandoning ordinary fused magnesia,in order to have a prolonged service life,increase the availability of the ladle and reduce the number of downtimes of the ladle.Free phenol in resin produced in China should be as low as that of resin made in Europe,to improve production environment and reduce smoke emission during the ladle preheating.There are large spaces to promote the productivity of magnesia-carbon bricks in China,with high intensity mixers and hydraulic presses.Expansion controlled magnesia-carbon bricks in the ladle depend on the optimized combination of sintered magnesia,Carbores and antioxidants as the matrix,to minimize the premature wear of vertical cracks and joint opening formed in the ladle lining.
文摘The residual expansion of in-situ spinel formation in using of alumina-magnesia-carbon(AMC)bricks monolizes the lining of steel-making ladles with the closure of their joints,which has been an effective solution avoiding washing out of the joints in ladle lining by the reduction of the penetration of liquid slag and molten steel.Alumina-magnesiacarbon refractories are overall reviewed,in terms of major raw materials,thermal evolution,corrosion and oxidation,and thermomechanical behavior,as well as type,addition and fraction of magnesia used.General commercial products contain 5%-10%MgO and 5%-10%C with a certain amount of metallic aluminum powder,which is believed to facilitate spinel formation at early stage of heating-up,although high magnesia containing AMC bricks are studied and used sometimes.With low ratio of Al_(2)O_(3)/C=12.9 and the carbon content of 6.4%C,AMC brick exhibits the highest corrosion resistance.It is important to determine the type,addition and fraction of magnesia used in AMC refractories for demonstrating high corrosion resistance and superior thermomechanical behavior.
