粗壮脉纹孢菌孢子中类胡萝卜素的体外发酵特性

模拟人体消化过程对粗壮脉纹孢菌孢子进行消化,通过酸热法提取消化后孢子粉中的类胡萝卜素,进行体外发酵。采用国标法测定发酵液的产气量、pH、NH3-N,采用气相色谱法测量发酵液中短链脂肪酸的含量。通过16SrRNA高通量测序技术分析志愿者肠道菌群,结果发现消化后的粗壮脉纹孢菌孢子粉中类胡萝卜素经体外发酵,pH值趋于6.0~7.2,与人体肠道pH值接近,产气量较少,不易引起胀气,可产生的乙酸、丙酸、丁酸等有益于人体健康的短链脂肪酸,使拟杆菌减少,变性杆菌增加。粗壮脉纹孢菌孢子粉中类胡萝卜素有利于改善人体肠道菌群,优化肠道菌群中各菌属的比例,有益于人体的肠道健康。     

Pressurized thermal shock analyses of a reactor pressure vessel using critical crack depth diagrams

Evaluated in this study is the pressure vessel integrity under a pressurized thermal shock. Using transient histories such as temperature, pressure and heat transfer coefficient, the stress distribution is calculated and then stress intensity factors are obtained for a wide range of crack sizes. The stress intensity factors are compared with the fracture toughness to check if cracking is expected to occur during the transient. Critical crack depth diagrams are prepared for each transient which is expected to initiate a pressurized thermal shock accident. Plant-specific analyses of the most limiting plant in Korea are performed to assure the structural integrity of the reactor vessel and the results are discussed.     

丝锥用Nb微合金化TGM2A-S高速钢的开发

TGM2A-S钢(/%:0.85C、0.27Si、0.24Mn、0.026P、0.007S、3.98Cr、4.76Mo、6.09W、1.83V、0.12Nb、0.03RE)是在高速钢TGM2A的基础上添加微量铌和稀土开发的新型丝锥用高速钢。TGM2A-S钢的生产工艺流程为25 t EAF-30 t LF-VD(微合金化)-铸锭(700 kg)二火锻造(85 mm方)-连轧(Φ8 mm)-冷拉(Φ6.6 mm)-加工丝锥(M6)。结果表明,原工艺:3 t中频感应炉-ESR (280 kg锭)-二火锻造(85 mm方)-连轧(Φ8 mm)-冷拉(Φ6.6 mm)-加工丝锥(M6)生产的TGM2A钢中的O和N含量分别为35.4×10^-6和123.6×10^-6,而改进工艺生产的TGM2A-S钢的O和N含量分别为15.7×10^-6和87.7×10^-6。TGM2A-S钢的丝锥切削寿命较电渣工艺生产的TGM2A钢提高20%; TGM2A-S钢的淬火晶粒为10.5级,电渣工艺生产的TGM2A钢的晶粒度为10级。     

M2高速钢的高温力学性能

在Gleeble- 3800热模拟机上进行了高速工具钢W6Mo5Cr4V2（M2）钢热模拟试验,测试了从650℃到1250℃温度M2钢的高温力学性能,得到了抗拉强度曲线和热塑性曲线,观察了不同温度下试样的金相组织和断口形貌。试验结果表明：M2高速钢的零塑性温度为1220℃,零强度温度为1250℃。良好的塑性温度区为950~1150℃,脆性区主要为1175℃至熔点,在850~950℃存在一个较弱的脆性区。在800℃附近,还存在一个良好的低温超塑性区。分析表明,M2高速钢的高温力学性能与基体组织的相变、碳化物的溶解和低熔点碳化物的熔化有很大关系。     

铈对D6冷作模具钢中共晶碳化物的影响

针对某集团生产的模铸D6钢中经常出现共晶碳化物对超标现象,在模铸过程中添加稀土元素铈.在坯料和钢材上取样,采用光学显微镜观察侵蚀后钢的组织形貌.结果表明,随着铈含量的增加,共晶碳化物网格尺寸变小,当坯料中铈含量由0.038％增加到0.073％时,网格尺寸减小约50％,网格厚度变薄,甚至网状结构被破坏;钢材中共晶碳化物的级别随铈含量的增加而降低.铈对铸态组织的细化作用导致了最终产品中共晶碳化物的细化.     

特种印版衬纸施胶工艺研究及生产探讨

介绍了一种特种印版衬纸应用阳离子分散松香胶在极端pH值条件下的施胶工艺,使产品达到具有较低成纸水抽提pH值的要求。     

Influence of Thermal Homogenization Treatment on Structure and Impact Toughness of H13 ESR Steel

The as-cast microstrueture of H13 ESR ingot and the influence of high temperature diffusion treatment on the structure and impact toughness have been investigated. The results show that the dendrite arm spacing gradually becomes wide from the surface to the center of ingot, and the large primary carbide particles always exist in interdendritic segregation areas; by means of high temperature diffusion treatment of ingot prior to hot forging, the banded segregation is nearly eliminated, the annealed structure is more uniform and the isotropic properties have been improved remarkably.     

Morphology,microstructure and decomposition behavior of M2 C carbides in high speed steel

The morphology, microstructure and decomposition behavior of M2 C carbides in high speed steels with different chemical compositions have been investigated by scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction and X-ray diffraction.The results show that the morphology and substructure of M2 C carbides are very sensitive to chemical compositions of high speed steels.M2 C carbides present the plate-like shape in tungsten-molybdenum steel and present the polycrystal orientation in the eutectic cell.In contrast, they show the fibrous shape in molybdenum-base steel and exhibit the monocrystal orientation.Plate-like and fibrous M2 C carbides are both metastable and decompose into M6 C together with MC at high temperatures.MC nucleates inside the plate-like M2 C while it is formed at the fibrous M2 C/matrix interface during the decomposition process.Such differences are expected to arise from different compositions of plate-like and fibrous M2 C carbides.     

摩擦焊刀具的热处理

国内外普遍采用摩擦焊生产工艺制造φ10mm以上的杆式刀具.同闪光焊相比,摩擦焊具有节电、焊缝质量好、结合强度高等优点,用摩擦焊生产的高速钢刀具可节材50%以上.但如果操作不当,也会出现质量问题,甚至批量报废.     

The reliability analysis of a thin-edge blade wear in the glass fiber cutting process

This study shows that the reliability analysis of a thin-edge blade plays an important role in cutting glass fiber and explores the main effect of three cutting factors: the cutting speed, the cutting load, and the cutting volume. The effect of each cutting factor on the thin-edge blade wear, as determined by long glass fiber weight, and exceeding a value of 1%, as specified in the customer's requirements, was investigated. According to the experimental results, the thin-edge blade wear distribution approximated to a Weibull distribution, and the cumulative probability could be determined after nine iterations. This study also finds that there is a large positive correlation among the various thin-edge blade-wear values at different cutting speeds. However, the correlation is negative for the various thin-edge blade-wear values when cutting at load, and when cutting at different cutting volumes. It was observed also that the optimum cutting speed with minimum thin-edge blade wear is 1.9 m/s. The successful deployment of this study will be a significant factor in improving the cutting process and cutting quality.