共查询到19条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
使用硫酸钙晶须对聚氨酯环氧树脂进行改性,研究改性前后、改性条件、晶须长度及晶须加入量对聚氨酯环氧树脂粘接性能的影响,并分析了晶须对聚氨酯环氧树脂的改性机制。实验结果表明,晶须对聚氨酯环氧树脂的改性机制为裂纹在晶须/基体界面处发生偏转,从而阻碍了裂纹的扩展。当使用长度较短、经有机化处理后的晶须对聚氨酯环氧树脂进行改性时,可使改性后的聚氨酯环氧树脂对LY12铝合金的粘结强度得到较大提高,其室温剥离强度提高27%,100℃及-70℃剪切强度分别提高了39%和10%,晶须对聚氨酯环氧树脂高温性能的改善尤为明显。 相似文献
5.
硫酸钙晶须改性氟橡胶复合材料的热稳定性 总被引:1,自引:0,他引:1
采用热分析技术研究了在氮气气氛中硫酸钙晶须(CSW)/氟橡胶(FPM)复合材料的非等温热分解行为及其动力学, 并与无水硫酸钙(ACS)/氟橡胶(FPM)复合材料进行了对比。通过Kissinger法和Ozawa法分别计算出其热分解活化能, 且结果相近。结果表明: Kissinger法计算的CSW/FPM复合材料的热分解活化能为203.33 kJ·mol-1, 高于ACS/FPM复合材料的热分解活化能(174.74 kJ·mol-1), 具有较高的热稳定性; 热分解反应级数约为1级。随着失重率的增大, 热分解活化能增大。 相似文献
6.
根据制备原料的不同,对目前硫酸钙晶须的制备方法进行阐述,并介绍了硫酸钙晶须在复合材料、水处理等领域的应用,从而提出了硫酸钙晶须在制备、应用等方面的未来发展方向。 相似文献
7.
8.
9.
10.
硫酸钙晶须催化合成一缩二乙二醇双甲基丙烯酸酯* 总被引:1,自引:0,他引:1
以一缩二乙二醇和甲基丙烯酸甲酯为主要原料,酯交换合成一缩二乙二醇双甲基丙烯酸酯.硫酸钙晶须对合成一缩二乙二醇双甲基丙烯酸酯具有高效催化作用,而半水和无水硫酸钙均没有催化活性.考察了甲基丙烯酸甲酯与一缩二乙二醇物质的量比、催化剂用量、阻聚剂用量等因素对收率的影响,得出了最佳反应条件:n(甲基丙烯酸甲酯);n(一缩二乙二醇)=3.5:1,反应温度为回流温度,催化剂硫酸钙晶须、阻聚剂氮氧自由基加入量分别为一缩二乙二醇质量的3%、0.1%.在此条件下合成的一缩二乙二醇双甲基丙烯酸酯的收率大于96.3%,纯度达97%. 相似文献
11.
12.
Surface modification of calcium metaphosphate fibers 总被引:2,自引:0,他引:2
Kasuga T Ota Y Nogami M Abe Y 《Journal of materials science. Materials in medicine》2000,11(4):223-225
-calcium metaphosphate fibers having high aspect ratios of 10–120 with diameters of 2–10 m show high strength and good biocompatibility. When the fibers are soaked in simulated body fluid at 37 °C, however, no calcium phosphate phase is newly formed on the fibers. In the present work, by treating the fibers at 70 °C with dilute NaOH aqueous solution, the surface phase was converted successfully into the orthophosphate phase that was in fine sizes and was adhered. After soaking the treated fibers in simulated body fluid at 37 °C for 30 days, a new calcium phosphate phase was precipitated. This was attributed to the surface phase modified using dilute NaOH. The treated fibers are expected to show bone-bonding ability, i.e. bioactivity. ©2000 Kluwer Academic Publishers 相似文献
13.
《Advanced Powder Technology》2017,28(8):1877-1881
Mechanochemical phenomena including mechanical activation and direct reaction have been widely observed particularly from dry grinding operation and various applications of the phenomena have been reported in many fields of chemistry. A new approach was introduced here to trigger partial reaction by co-grinding samples with small addition of water/liquid to achieve the purpose of surface modification with new phase formed. As one example, basic copper carbonate was wet ground with elemental sulfur and appropriate additives such as ammonium sulfate to transform the surface chemical composition from oxide to sulfide. Physicochemical characterizations of the prepared samples were conducted by a set of analytical methods, including X-ray diffraction analysis, Fourier Transform infrared spectroscopy, Raman spectroscopic analysis, SEM morphology analysis, Zeta potential and the dissolved copper concentration measurement. The beneficiation efficiency of the modified copper carbonate by a conventional froth flotation used usually for sulfide minerals was examined as a quantitative evaluation to optimize the experimental conditions for the modification operation. A metal yield over 80% was obtained easily after one step concentrating of the flotation operation, indicating that mechanochemically surface controlling concept may serve as a novel pathway to enrich and recycle carbonate-style nonferrous resources by applying the traditional mineral processing technology on the modified samples. 相似文献
14.
15.
Abstracts are not published in this journal
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
16.
An areal heat source can be generated by the line-shaped, high frequency scanning of an electron probe. Its use for tasks in the thermal modification of surfaces allows for an advantageous separation of the heating and cooling fronts. Moreover, the use of an elliptic distortion of the focal spot results in an enhanced throughput for penetration depths that greatly exceed the electron range. The application of this technique is explained by way of examples taken from the fields of microelectronics and the metalworking industries. Various aspects concerning the use of laser beams and electron beams for thermal surface modification are discussed. 相似文献
17.
A modification of tape casting for aligning the whiskers 总被引:2,自引:0,他引:2
Tape casting was modified in order to align the silicon nitride whiskers in the silicon nitride slurry. Based on a simplified fluid dynamics model, it was understood that torque for aligning the whisker was increased by n2 times by dividing the flow into n narrow ones. Samples with 3 wt % silicon nitride whiskers of a hexagonal crystal structure were prepared by using three different tape casting methods; conventional tape casting, tape casting modified by using an array of razor blades, and tape casting modified by using an array of sharpened pins. The razor blades of 13 mm in length were 5 mm apart from each other in the array, and the sharpened pins of 0.08 mm in diameter 0.7 mm apart from each other in the array. Samples were fully densified by gas pressure sintering. Both the sintering shrinkage anisotropy and X-ray diffraction analysis showed that the sample prepared by employing the pins had the best whisker alignment among the three samples. 相似文献
18.
19.
Joe E. Jenkins 《Thin solid films》1981,84(4):341-346
Experiments were conducted with three common steels, namely AISI 1045, AISI 4150 and AISI 1090, using an electron beam as an energy source to provide rapid superficial surface fusion. Beam scanning velocities of 75–2592 cm s-1 were used. Increasing the beam scan rate resulted in an increased hardness for scan rates of up to 1300 cm s-1. This scan rate gives a calculated cooling rate in excess of 107 °Cs-1.Microhardness was used as a measure of the performance resulting from the rapid solidification rates obtained. The measured Vickers hardness was converted to and reported as the Rockwell C scale hardness.The fused layer appears as a metastable solid solution with a fine precipitate associated with the overlap of fused paths. The Vickers hardness was found to be significantly harder (1100 HV compared with 700 HV) than that of the same materials treated by a conventional quench. The treated layer also appears to have good fracture toughness in that adjacent and superimposed hardness indentations and those near an edge did not induce cracking.Post-fusion thermal treatments at 200 and 590 °C and a complete quench and temper all resulted in a lower measured hardness. 相似文献