铸铁件消失模充型速度的测试及计算

使用计算机数据采集系统测试了铸件消失模充型过程中负压度、模样密度、浇注温度、金属静压头等工艺因素对充型速度的影响规律。通过多元线性回归，给出了充型速度的经验计算公式，并对公式进行了验证。     

Temperature distribution and dynamic control of secondary cooling in slab continuous casting

To predict and optimize the temperature distribution of slab continuous casting in steady operational state, a three-dimensional model (named offline model) based on the heat transfer and solidification theories was developed. Both heat transfer and flux distribution characteristics of the nozzle sprays on the slab were considered, and the complicated boundary condi-tions, such as spray cooling, natural convection, thermal radiation as well as contact cooling of individual rolls were involved in the model. ...     

连铸大方坯凝固传热过程的数值模拟

基于凝固传热学基本理论,建立了大方坯凝固传热数学模型。该模型根据糊状区溶质传输和反扩散理论,基于变热物性参数,采用钢中多组元成分的百分含量计算液、固相线温度。以实际铸坯为对象,以二冷区铸坯表面实际水流密度分布和辊子接触传热为边界条件,充分考虑二冷区的四种不同的换热状况,研究连铸大方坯三维温度场。计算结果与实测温度吻合。     

镁合金表面覆盖层形成方法及相关国家标准

镁合金具有优异的比强度,但耐蚀性较差,很少在铸态下直接使用,需要进行表面处理以形成防护性覆盖层.本文对现有的镁合金表面覆盖层形成方法,如电化学镀、化学转化、阳极氧化、气相沉积、激光表面改性和有机涂层等,进行了评述.国家标准对相关技术等具有极强的指导意义,而目前系统介绍有关我国国家标准中涉及表面处理方面的资料很少,所以本文也针对目前国家标准中表面处理工艺、检测方法等进行简单的介绍.     

Analysis of internal crack in a six-ton P91 ingot

P91 is a new kind of heat-resistant and high-tensile steel. It can be extruded after ingot casting and can be widely used for different pipes in power plants. However, due to its mushy freezing characteristics, a lack of feeding in the ingot center often generates many defects, such as porosity and crack. A six-ton P91 ingot was cast and sliced, and a representative part of the longitudinal section was inspected in more detail. The morphology of crack-like defects was examined by X-ray high energy industrial CT and reconstructed by 3D software. There are f ive main portions of defects larger than 200 mm~3, four of which are interconnected. These initiated from continuous liquid f ilm, and then were torn apart by excessive tensile stress within the brittle temperature range(BTR). The 3D FEM analysis of thermo-mechanical simulation was carried out to analyze the formation of porosity and internal crack defects. The results of shrinkage porosity and Niyama values revealed that the center of the ingot suffers from inadequate feeding. Several criteria based on thermal and mechanical models were used to evaluate the susceptibility of hot crack formation. The Clyne and Davies' criterion and Katgerman's criterion successfully predicted the high hot crack susceptibility in the ingot center. Six typical locations in the longitudinal section had been chosen for analysis of the stresses and strains evolution during the BTR. Locations in the defects region showed the highest tensile stresses and relative high strain values, while other locations showed either low tensile stresses or low strain values. In conclusion, hot crack develops only when stress and strain exceed a threshold value at the same time during the BTR.     

用异丙醇精制胆固醇

选用异丙醇分别重结晶熔点140℃和147℃的胆固醇,优化了所用异丙醇的最佳质量分数为75%,重结晶时胆固醇溶解完全,单步收率达到92.0%,所得产品指标分别达到147℃胆固醇和液晶用胆固醇的质量要求,并将异丙醇和其他常用胆固醇精制方法作了比较。     

连续铸造板坯结晶器中流动与液位波动模拟研究

采用SIMPLER迭代方法进行数值计算,针对连续铸造过程中的结晶器内部紊流流场和结晶器弯月面表面的液位波动情况,进行了三维数值模拟和水模拟试验验证,并使用表面动能法定量表征液面波动情况.通过对不同拉速、水口浸没深度和水口出流角度下的紊流流场及液位波动情况的模拟计算,分析各工艺参数对于连续铸造结晶器内部流场分部和表面波动幅度的影响,为合理地设计水口结构和选取合适的浇铸工艺参数提供了可靠的理论依据.     

连铸结晶器内大方坯的热力耦合分析

针对攀钢大方坯连铸机投产初期铸坯表面角部纵裂缺陷,建立了大方坯连铸结晶器内铜板与铸坯问的热力耦合模型,应用模型分析了大方坯连铸结晶器内的传热过程和坯壳的应力分布.在传热模型中,以稳态模型分析结晶器的传热过程,以瞬态模型分析铸坯的传热过程;在力学模型中,考虑铸坯和结晶器的接触边界以处理结晶器角部的气隙,以热弹塑性模型分析铸坯的变形和应力场.2种结构的连铸结晶器中大方坯温度场和应力场计算结果表明,结晶器倒角从25 mm×45°变为12 mm×45°时,可改善铸坯角部的传热条件,降低凝固坯壳角部温度,增加凝固坯壳厚度,有利于减轻和防止铸坯角部裂纹.     

125I粒子植入术治疗转移性骨痛的临床应用

【摘要】目的初步探讨放射性粒子植入术治疗骨转移瘤所致骨痛的疗效。方法诊治52例骨转移瘤患者,在CT引导下行125I放射性粒子植入治疗。结果125I放射性粒子植入后,第2天患者疼痛感明显减轻;第5~7天患者胀痛感加重;术后10~30 d患者疼痛逐渐缓解。术后1个月疗效评估:Ⅰ级疼痛缓解率100%,Ⅱ级疼痛缓解率88.9%,Ⅲ级疼痛缓解率92.3%,总有效率93.7%（P＜0.05）。对不同疼痛程度患者局部疼痛缓解有效率高,但Ⅱ、Ⅲ级疼痛缓解率无明显差异（P=0.369）。结论125I放射性粒子植入治疗骨转移瘤所致骨痛,治疗时间短、短期内缓解疼痛疗效明显且并发症少。特别对于溶骨型骨转移瘤,其治疗效果较好,在临床保守治疗疼痛控制不理想时,125I放射性粒子植入可作为一种有效的治疗方法。