X80管线钢钙处理后软吹时间对夹杂物行为的影响

探讨了钙处理后软吹40 min过程X80管线钢夹杂物的行为变化.结果表明,软吹前25min,钢中总氧含量由0.001 2％降低到0.000 8％;软吹25 min至40 min,钢中总氧含量略有回升.钢中夹杂物的数量随着软吹时间的增加而减少,软吹25 min后较大尺寸夹杂物基本去除完毕.继续增加软吹时间,有利于进一步去除钢中尺寸在1～5 μm的夹杂物.随软吹时间的延长钢水温降增大,利于CaS夹杂物的生成,对后续浇注不利.综合考虑夹杂物的去除效果和软吹过程的温降等因素,认为管线钢钙处理后软吹时间控制在20 ～25 min较为合理.     

碳素钢中氧含量与氧化物分量的测定及其对应关系的探讨

借助氧氮分析仪的程序升温功能,研究了样品表面裂纹对氧含量测定的影响及碳素钢中氧含量的释放特征,探讨了其中不同氧化物与分解释放温度的对应关系。采用氧氮分析仪的温度维持程序升温模式,测定了碳素钢裂纹样品中的氧含量,对其升温曲线和氧释放曲线进行分析,结果表明:碳素钢中氧的释放峰通常分为低(1 800 ℃以下)、中(1 950 ℃左右)、高(2 200 ℃左右)3个温度区段;裂纹的存在只影响小于1 800 ℃的低温段氧含量,对不小于1 800 ℃的中、高温度平台内氧释放峰位置与强度(氧含量)没有影响。实验建立了合理的分步阶梯程序升温参数,用分步阶梯程序升温模式测定了表面裂纹样品和表面洁净的正常样品中氧含量分量,结果表明,碳素钢样品的低温段氧含量为样品内部存在的少量低温氧化物中氧和固溶氧两部分的合量;中、高温段氧含量之和不受制样方法、样品状态或样品表面质量的影响。进行了碳素钢中可能存在氧化物的脉冲熔融分解温度模拟试验,探讨了其中氧含量分量与不同氧化物的对应关系。结果表明,碳素钢中FeO、MnO、NiO、Fe₂O₃等分解温度均低于1 800 ℃;经分步阶梯升温方式扣除小于1 800 ℃的氧释放峰后,中、高温段释放峰所对应的氧含量与钢中各类氧化物夹杂的含量(如SiO₂、Al₂O₃、CaO及其复杂化合物)直接相关。     

真空条件下钢液脱气过程的模拟研究

基于相似的动力学机理,利用水溶液中溶解氧的去除过程模拟了钢液的真空脱气行为. 在负压25 kPa条件下发现,容器壁面或测氧探头表面会析出大量细小气泡,这一现象与以往脱气数学模型假设的内部脱气反应非常类似;为了验证内部脱气位点的存在,通过引入机械搅拌,对溶池表面和内部脱气速率进行了分析计算. 实验结果表明,在整个脱气过程中溶池表面脱气速率很低,内部脱气位点析出的气泡会极大地提高溶解氧的去除速率,尤其当真空压力为25 kPa时,其脱气速率约为自由表面的脱气速率的10倍,但内部反应仅局限于脱气的初始阶段,即高溶解氧浓度范围内. 另外,水溶液中溶解氧的去除为一级反应过程,其体积传质系数（k · A · V?1）为常数,因此可以利用溶解氧在水溶液中的去除过程模拟钢液的真空脱气行为. 为了描述真空压力和吹氩流量对k · A · V?1的影响,引入搅拌动能密度（ε）的概念,通过线性回归得到了lg (k · A · V?1)与lg ε之间的函数关系,并与以往的模拟研究进行了对比.      

钢中氢的分析方法优化

通过对国外氢测定仪的脱氢周期、脱气时间、脱气功率、分析功率等仪器参数进行试验设计,摸索出满足国产耗材测定钢中氢元素的最佳分析方法。采用4因素、2水平的正交试验设计选择了最佳测定条件为:脱气周期2次、分析延迟30s、脱气时间20s、脱气功率5.5kW,克服了因国产石墨坩埚空白值不稳定对钢中氢元素分析结果的影响。该方法应用到生产中,测定值与认定值相符合,标准偏差小于0.26μg/g。     

Ⅵ精炼钢的夹杂物及其对大锻件质量的影响

为了提高大锻件用钢质量,控制夹杂物形态、尺寸、数量并使其均匀分布十分重要。Ⅵ法的实质就是在RH真空脱气过程中进行钢包喷粉。Ⅵ处理以后,钢中的夹杂物呈球状,其数量明显减少。用图象分析方法测定夹杂物面积百分数为0.02～0.03％,夹杂物平均尺寸为2～4μm。大量生产数据的统计分析表明,钢中夹杂物的数量与钢中氧含量、出钢温度及Ⅵ处理时间的自然对数的倒数有正相关关系。夹杂物尺寸与钢包砖缝泥料中SiO_2％及Ⅵ处理时间亦有正相关关系。     

惰气熔融-红外吸收法测定硅钙合金中氧

硅钙合金作为钢铁和特殊合金生产过程中重要的脱氧剂和脱硫剂,目前还没有氧含量测定的国家标准方法。实验采用脉冲加热惰性气体熔融-红外吸收法建立了硅钙合金中氧含量的测定方法。考察样品粒度对分析结果精度的影响,确定最优粒度范围为120～150目(0.121～0.104 mm);进行了称样量条件试验,确定称取0.02 g试样最为合适;另外还考察分析功率条件和助熔剂的影响,确定5 000 W时,脉冲炉工作电流至少达到1080 A左右,采用镍箔作为助熔剂,包裹样品,样品熔融良好,释放完全。选择与待测样品氧含量接近的高氧铁粉参考物质JK47 (w(O)=1.09%),采用不同称样量,建立校准曲线,曲线的相关系数为0.995 1。结合校准曲线,确定方法的测定范围为0.2%~10%,方法的测定下限为0.000 41%。对硅钙合金样品进行精密度考察,氧测定结果的相对标准偏差(RSD)为1%左右,满足生产要求。采用高纯SiO₂和CaO进行回收实验,回收率在95%～105%之间。     

惰气熔融-红外法测定钛毛细管中氧含量的制样方法

钛毛细管是一种形状特别的钛合金，由于其内径常小于1 mm，管壁厚度不足1 mm，表面积较大易被污染，而且钛毛细管在加工过程中表面很容易因发热氧化，因此在进行钛毛细管氧含量测定时表面油污及氧化层的处理尤为重要.试验中选择依次使用HNO3-HF混合酸、蒸馏水、丙酮于超声波清洗仪中处理试样，使用惰气熔融-红外法进行了精密度和加标回收试验，结果满意.      

基于扫描电镜的反渗透基膜孔径测量方法研究

文章使用溅射镀膜仪对反渗透基膜进行喷金处理,探索最佳喷金参数,改善样品导电性;使用场发射扫描电镜和Image J软件对膜样的孔径进行测量分析。研究结果表明:喷金处理对反渗透基膜的扫描电镜图像质量具有重要影响,喷金处理既要能够改善样品表面导电性,又要避免金薄膜覆盖样品的原始形貌。最佳喷金参数为:溅射距离55 mm,溅射电流15 m A,溅射时间10 s。三种反渗透基膜中,1#和2#样品中,6.5 nm到10 nm孔径的数量分别为68.8%和58.1%;3#样品中小于或等于10 nm孔径的数量为19.7%,大于10 nm孔径的数量为80.3%。高分辨扫描电镜成像和Image J软件,结合最佳喷金处理,能够对反渗透基膜几纳米到几十纳米孔径进行有效测量。     

高频燃烧红外吸收法测定炭/炭复合材料中碳

采用高频感应炉燃烧红外吸收碳硫仪,建立了炭/炭复合材料中碳的测定方法。对测定条件如助熔剂、称样量、分析时间等进行了优化研究。其最佳测定条件为:样品称量为0.15 g左右;最大工作电流350 mA,载气流速为3 L/min,载气(氧气)纯度99.99%,陶瓷坩埚需经1 100℃灼烧2 h后,可使空白降至最小,预清洗时间10 s,预延时间10 s,碳元素最短分析时间为60 s,比较水平为1.0%。该方法快速、简便,具有良好的精密度和准确度,用于复合材料中碳的测定,RSD为0.10%～0.21%。     

降低汽车齿轮钢氧含量的工艺实践

分析和研究了用 30 t EBT电弧炉 40 t LFV精炼工艺冶炼Mn Cr、Cr Mo、Cr Ni Mo系等汽车用新型齿轮钢时 ,真空度、精炼渣、吹Ar工艺和 [Al]s对钢中氧含量的影响 ,得出真空度小于10 × 133Pa ,吹Ar 100～150 L/min ,精炼渣碱度25～30 ,控制 [Al]s为0.02%～0.04%时可以获得低氧含量。生产结果表明 ,Mn-Cr系、Cr-Mo系和Cr-Ni-Mo系齿轮钢氧含量为(12～20 )× 10^-6 ,达到汽车用新型齿轮钢氧含量的标准要求     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

参与式农业基地建设行动方案设计

为了编制实用性强的基地建设行动方案,首先,确定参与式发展的主体,搭建一个"决策框架";其次,针对行动目标,提出不同参与主体,如管理者、农民、消费者等团队与个人的目标及行动内容;最后,工作应向重塑伙伴式合作关系,挖掘农民自我发展潜力,完成三大角色的转换,打造农业基地文化等方向推进.