粉末冶金法制备梯度多孔Mg-Ca合金

采用粉末冶金法以碳酸氢铵为造孔剂、镁粉和钙粉为原料,制备了梯度多孔Mg-Ca合金。研究了造孔剂含量、分布和烧结温度对梯度多孔Mg-Ca合金孔隙特性的影响。测量了烧结产物的弯曲性能。研究结果表明随着中间层造孔剂含量的降低,孔隙梯度分布加大,试样的平均孔隙度降低,但梯度孔隙结构导致试样的抗弯强度增加。此外,随着烧结温度的升高,梯度多孔Mg-Ca合金的平均孔隙度降低,抗弯强度增加。XRD和SEM观察结果都表明,烧结产物中没有造孔剂碳酸氢铵的残留,主要有Mg和Mg2Ca两相组成。     

真空烧结温度对多孔钛影响的研究

以碳酸氢铵做造孔剂,采用真空烧结法制备出生物多孔钛．研究了烧结温度对多孔钛显微形貌、显气孔率、抗压强度的影响．研究表明,提高烧结温度,有利于Ti晶体的发育,并提高制品抗压强度．     

氧化铝透气陶瓷及透气性研究

研究添加造孔剂法和干压成型法制备氧化铝多孔透气陶瓷。以氧化铝为原料,分别用淀粉、蔗糖、蛋清作为造孔剂,用聚乙烯醇做粘结剂,在1700℃下烧结制得以开孔为主的氧化铝多孔透气陶瓷。通过抗弯曲强度测试检测样品的力学性能;利用X射线衍射分析(XRD)、扫描电镜(SEM)表征其物相成分、显微结构,对透气性进行测试。实验结果表明:试样的抗压强度随造孔剂的增多而减小;抗弯曲强度不随造孔剂的增多而增大,但是造孔剂含量过大时作用相反;烧结后试样的主要成分是α-Al2O3。用淀粉(10%)做造孔剂制得的样品具有较好的力学性能且气孔分布均匀.     

氯化钠作为造孔剂制备含氯多孔羟基磷灰石实验研究

采用化学沉淀法,制备纳米HA粉体．采用造孔剂法,首次利用NaCl作造孔剂,将纳米HA粉体和NaCl颗粒按一定比例混合压制成型,经高温烧结制备出多孔含NaCl的HA材料．利用XRD、SEM、EDX手段研究多孔HA的组成成分、微观形貌、孔径尺寸及孔隙率．研究结果表明：NaCl是比较理想的造孔剂材料,可制备孔隙率、孔径尺寸、形貌可控的多孔材料．造孔剂含量为30％,尺寸在160～200目时,造孔效果最好;在烧结温度1200℃烧结时,NaCl会与HA发生反应,生成Ca5（PO4）3Cl,Ca9．54P5．98O23．58Cl1．6（OH）2．74等新的物相．     

烧结温度对BaTiO3多孔陶瓷性能的影响

采用水基冷冻浇注法制备了具有层状结构的BaTiO3多孔陶瓷,研究了烧结温度对多孔陶瓷微观形貌、收缩率、孔隙率及介电性能的影响,并探讨了高岭土悬浮剂在烧结过程中所起的作用.研究结果表明:高岭土含量4wt%的样品收缩率从1 200℃时的27%升高到1 220℃时的56%,同时孔隙率从78%下降到56%,高岭土含量8wt%的样品收缩率从1 200℃时的30%升高到1 220℃时的61%,同时孔隙率从72%下降到39%;高岭土在烧结过程中起到烧结助剂的作用;烧结温度升高会使孔径变小并导致孔隙排列由有序结构向无序结构转变.高岭土含量为8wt%,烧结温度1 200℃时,可以得到分布均匀的层状结构多孔陶瓷;高岭土含量为4wt%,烧结温度1 220℃时可得到介电常数130的多孔陶瓷.     

硅藻土基孔梯度陶瓷的制备

以硅藻土、高岭土和硅灰石为膜层坯料,通过探究烧结温度对膜层显微结构、显气孔率和抗弯强度的影响,确定最佳烧结温度为1 140℃。以碳酸锂为助烧剂,淀粉为造孔剂加入到上述坯料中作为支撑体坯料,将不同配比的两种坯料层压成型,在高温下烧结,成功制备了层状孔梯度多孔陶瓷材料。结果表明,该孔梯度陶瓷具有较高的显气孔率和较高的抗弯强度,抗弯强度达到15.7 MPa。膜层中无造孔剂添加,显气孔率为55.4%;支撑体层以淀粉为造孔剂,显气孔率为59.6%。     

用粉煤灰为主要原料制备多孔陶瓷研究

以工业废弃物粉煤灰为主要原料,氧化铝为辅料,玻璃粉为粘结剂,不可溶性淀粉为造孔剂,利用不同配比的粉煤灰、氧化铝及造孔剂,干压成型得到柱状坯体,经高温烧结制得多孔陶瓷。采用正交试验研究了氧化铝用量、成型压力、粘结剂用量、造孔剂用量和烧结温度对多孔陶瓷性能的影响。研究结果表明:烧结温度和造孔剂用量对多孔陶瓷性能的影响最大。在最优试验配方和工艺参数下,即氧化铝用量比例0.4(氧化铝与粉煤灰质量之比,下同)、成型压力18 MPa、粘结剂用量6%(占总重百分比,下同)、造孔剂用量6%(占总重百分比,下同)、烧成温度1200℃下,制备的多孔陶瓷样品具有抗弯强度为8.23MPa,孔隙率为37.65%,吸水率为22.61%,耐酸性为96.89%,耐碱性为96.86%,密度为1.69 g/ml。     

孔形貌与大小对羟基磷灰石多孔生物陶瓷力学性能的影响

本文采用图像处理和有限元分析的方法,针对孔隙形状和大小对多孔HAP生物陶瓷力学性能的影响进行了研究,多孔HAP陶瓷粉末来源于化学沉淀法制备的球形HAP。结果表明,随烧结温度从1 050℃升高到1 250℃,陶瓷内部互连的无定形孔的数量减少,球形孔的数量增加。有限元分析表明,越接近球形的孔,陶瓷的抗压强度越高,当烧结温度升高到1 250℃时,样品的断裂韧性增加为1.21 MPa m~(1/2),球形孔隙可提高多孔体的强度,赋予多孔体更好的抗断裂能力。     

利用淤泥和秸秆制备蓄水用轻集料的研究

以淤泥为原料,秸秆为造孔剂,废弃玻璃粉作为高温液相促进剂,硅酸钠作为塑性增强剂,高温烧结制备蓄水用轻集料。测试了轻集料的蓄水性能,用XRD分析了试样在烧结时的物相变化,用SEM分析了烧结温度对试样内部结构的影响。结果表明:用淤泥制备蓄水用轻集料时,最合适的秸秆掺量为30%,废玻璃粉为2.5%,硅酸钠为0.5%,在900℃下烧结20min,所得样品蓄水率达到80%以上。随着烧结温度的提高和保温时间的延长,蓄水材料的吸水率逐渐减小,抗压强度逐渐增加。XRD分析显示烧结试样中主要晶相为石英、钙长石和硅酸三钙。SEM分析表明烧结温度升高使得试样内部结构变得致密。     

宏孔性多孔玻璃载体颗粒的制备

利用填充法直接制备宏孔的多孔玻璃载体颗粒，探讨了造孔剂的种类及含量和烧结过程对颗粒的粒度分布、孔隙率、孔径分布及机械强度的影响，确定了复配造孔剂的适宜比例和工艺条件。结果表明，采用复配造孔剂解决了宏孔颗粒的强度与孔隙率、孔径的矛盾，在烧结温度800℃左右，保温时间2h的条件下，保证孔径在60－180μm，孔隙率稳定在40％以上，而强度达到2.4MPa以上。     

氮化硅结合碳化硅多孔陶瓷支撑体的制备与表征

以碳化硅、硅粉为主要原料,以氧化铝和氧化钇为烧结助剂,通过添加不同质量分数的淀粉为造孔剂,采用反应烧结方式制备了系列氮化硅结合碳化硅多孔陶瓷支撑体,并对烧成样品的物相、显微结构、孔隙率、抗折强度、孔径分布、纯水通量和耐酸碱性能进行了分析和表征. 结果表明,样品的主晶相为碳化硅和氮化硅,还有少量的焦硅酸钇和塞隆;随着淀粉质量分数的增加,样品的孔隙率随之增大,样品的抗折强度随之减小,同时样品的平均孔径和纯水通量随淀粉质量分数的增加均呈现先增大后减小的趋势;样品有良好的耐酸碱性能,在标准酸性和碱性条件下的质量损失率分别为1.96%~2.04%、3.96%~4.13%;当淀粉的质量分数为3%时,烧成样品的孔隙率为41.8%,抗折强度为18.1 MPa,孔径主要分布在0.7 μm~2.5 μm之间,纯水通量最高,可达9.2 m³/（m2*h）,综合性能较佳.     

Structure and mechanical properties of Ni-based porous superalloy

The porous superalloy materials with hollow spherical and oriented linear pores were fabricated by means of powder metallurgy using Ni-based superalloy powders. Structure observation revealed that the pores of the porous material exhibited uniform distribution and the pores were of the same size in principle. The sintering necks created between adjacent particles on metal skeleton after sintering. The porosity of the porous material increased with increasing the addition of pore forming agent, and the hollow spherical porous material with a porosity of 81.62% were obtained when the addition of pore forming agent was 40%. The compression test indicated that this kind of materials possesses excellent, energy absorption capability and the compression resistance decreased with the increasing of porosity and pore size.     

碳酸氢氨对壳聚糖粉体/医用聚氨酯复合支架结构和性能的影响

本文选择碳酸氢氨(NH4HCO3)作为发泡剂,采用湿法相转化法制得壳聚糖粉体/聚氨酯多孔支架材料,研究了NH4HCO3含量对支架的结构和性能的影响。结果表明随着NH4HCO3含量的不断增加支架材料的孔隙率和溶胀度不断增加,支架表面变得更加平滑细密,且NH4HCO3对壳聚糖粉体/医用聚氨酯复合支架材料的生物降解性能影响不大。     

Structure and Mechanical Properties of Ni-based Porous Superalloy

The porous superalloy materials with hollow spherical and oriented linear pores were fabricated by means of powder metallurgy using Ni-based superalloy powders. Structure observation revealed that the pores of the porous material exhibited uniform distribution and the pores were of the same size in principle. The sintering necks created between adjacent particles on metal skeleton after sintering. The porosity of the porous material increased with increasing the addition of pore forming agent, and the hollo...     

Influence of Thermally Treated Flue Gas Desulfurization （FGD） Gypsum on Performance of the Slag Powder Concrete

The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200℃ for 60 min and then mixed with the slag powder to form FGD gypsum-slag powder combined admixture in which the SO3 content was 3.5wt%. Cement was partially and equivalently replaced by slag powder alone or FGD gypsum-slag powder, at concentration of 25wt%, 40wt%, and 50wt%, respectively. The setting times, hydration products, total porosity and pore size distributions of the paste were determined. The compressive strength and drying shrinkage of cement mortar and concrete were also tested. The experimental results show that, in the presence of FGD gypsum, the setting times are much slower than those of pastes in the absence of FGD gypsum. The combination of FGD gypsum and slag powder provides synergistic benefits above that of slag powder alone. The addition of FGD gypsum provides benefit by promoting ettringite formation and forms a compact microstructure, increasing the compressive strength and reduces the drying shrinkage of cement mortar and concrete.