一种造孔材料对金刚石薄壁钻头效率提高的研究

研究造孔材料N对Co胎体的强度和硬度的影响,并将N分别添加到纯Co、FeCu和CoFe基胎体中做成薄壁钻头,进行钻进钢筋混凝土的对比试验。结果表明:在纯Co胎体中加入N,随着添加量增加,抗弯强度和硬度均呈下降趋势,添加量到4%,抗弯强度下降16%,添加量到6%降低35%。钻进试验结果:不同的实验钻头钻进钢筋的效率均有提高,其中纯Co胎体提高102%;钻进纯混凝土,不同的胎体效果不同,纯Co中效率提高62%。

用于窑法还原磷矿的新型反应层球团的研究

研究了一种用于窑法磷酸工艺的新型反应层球团。通过热分析分别确定了焦炭(C)及一氧化碳(CO)还原磷矿时所需的温度,以及钙硅比(CaO与SiO_2摩尔比)对焦炭(C)还原磷矿的影响。研究了球团反应层中造孔材料掺量及炉内空气流速对磷矿还原率的影响,并对反应后残球的容重及抗压强度进行了测定。结果表明:高温下焦炭(C)和CO均能还原磷矿;随着球团反应层中造孔材料掺量及炉内空气流速的增大,磷矿还原率均呈现先增大后减小的趋势。炉内空气流速为500 m L/min时,球团造孔材料掺量与钙硅比分别为8%和1.0的球团在1300℃下煅烧反应3.5 h后,其磷矿还原率可达84.14%。

球形中空催化剂载体的制备

制备了一种用于制造球形中空催化剂载体的造孔材料。用正交实验的方法选择了造孔材料的原料配比,得到最佳制备条件为:造孔材料的质量组成为:15%A(A l2O3)、15%B(NH4HCO3)、8%C(C6H7O6Na)和62%D(H2O)。用造孔材料做球种制造的中空球形催化剂载体的理化性能基本与实心相差不大,抗压强度略有下降,堆积密度的大幅度下降能够满足生产的需要。

Volume change of macropores of titanium foams during sintering

The porosity of titanium foams obtained from the space holder technique was theoretically analyzed in the cases of volume shrinking, retaining and expanding during sintering. The relationship between porosity and spacer content was compared under different conditions. The kind of volume change of macropores during sintering was discussed. The results indicate that the relationship between porosity and spacer content depends on the decreased volume of macropores and the volume of micropores in cell-walls in the first case, while the porosity will be greater than the spacer content for the other two cases. It proves that the volume change of macropores during sintering decreases based on theory and practice.

Microstructure and mechanical properties of aluminium metal matrix composites with addition of bamboo leaf ash by stir casting method

Al-4.5%Cu alloy was used as a matrix at2%,4%and6%of bamboo leaf ash(BLA)which was extruded from agro waste and was used as reinforcement.The composite which was fabricated by stir casting method possessed superior properties due to an effective bonding between matrix and reinforcement particles.The fabricated composite specimens were subjected to various tests to determine the mechanical properties such as density,porosity,hardness and tensile strength.The results were compared with basic matrix alloy.Furthermore,the OM,SEM with EDAX and XRD analyses were carried out to analyze the dispersion of the reinforced particles in the selected matrix alloy.It was observed that the homogeneous distribution of BLA particles in composites was intragranular in nature.Moreover,it was also observed that BLA particles were well bonded with matrix alloy with clear interface.It was also found that the density decreased with increase in mass fraction of BLA particles and porosity increased with increase in mass fraction of BLA particles.The hardness and tensile strength were increased up to4%of BLA in the composite,with a further increase in BLA content the hardness and tensile strength decreased.

Analysis of Cutout Fiber as Source of Delamination in Composites System Using FEM

Delamination in composite structures can be a serious threat to the safety of the structure. Delamination leads to loss of stiffness and strength of laminates under some conditions. This is particularly so in the case of compressively loaded structures as the loss of stiffness may lead to separation of layers, the consequences of which can be catastrophic. Causes of delamination are many. In aerospace applications, this includes manufacturing defects, as well as operationally induced defects such as bird strikes, hits due to runway debris and tool drops. In this work one of the main causes of delamination that is dealt with, is the one that redistribution of the stress state due to some defects all mostly like here is broken single fiber （cutout fiber） in composite system already initiated by one of the above causes. When a laminate is subjected to in-plane tension, the effects of delamination on the stiffness and strength may be characterized by analytical results concerning the onset of delamination growth and its subsequent development. Many of the analytical treatments deal with just free-edge delamination. In mean time the redistribution and the gradient of the stress state in composite system is playing an important role for causing delamination. The main task of this work is to analyze single fiber with and without cutout embedded in matrix. Different FE models were generated, from the results, the redistribution of the stress state around the defected fiber were presented and discussed. Finally concluded remarks were indicated.