共查询到19条相似文献,搜索用时 113 毫秒
1.
AlOOH对Al2O3直接凝固注模成型坯体强度等性能影响 总被引:6,自引:0,他引:6
为了改善直接注模成型(DCC)氧化铝的坯体性能,在Al2O3-DCC过程中加入AlOOH本文详细研究了Al2O3+AlOOH体系的湿坯性能,干燥行为及烧结致密化过程,结果表明,少量AlOOH加入可显著提高Al2O3的湿坯抗压强度和弹性模量,当AlOOH体积含量〈3.0%时对干燥过程没有影响,干燥坯体经无压烧结后可获得烧结密度达3.97g/cm^3(99.7%TD)。显微结构均匀的α-Al2O3相。 相似文献
2.
3.
本论文研究了三氧化二铝(Al2O3)与羟基磷灰石(HA)及其复合体浆料的粘度及流动性,发现Al2O3能够显著地提高HA浆料的流动性,并降低其粘度,较好地满足三维选区凝胶成型的需要,根据实验结果,结合DLVO理论,提出了HA与Al2O3协同作用的模型。 相似文献
4.
为了实现Al2O3和羟基磷灰石(HAP)的同步烧结,必须降底Al2O3的烧结温度,选用具有生物活性和较低熔点的A/W生物玻璃作为Al2O3液相烧结的添加剂,利用流延成型工艺,制得了适合流延成型的水基A/W-Al2O3浆料及流延膜,分析了影响浆料及流延成型的各种因素。在烧结过程中,由于玻璃挥发而导致失重,所以样品的密度受烧结温度和烧结时间的影响,但在1300℃时,10wt%A/W-Al2O3的烧结密 相似文献
5.
AlOOH对Al_2O_3直接凝固注模成型的动电特性、流变性及凝固过程的影响 总被引:1,自引:0,他引:1
直接凝固注模成型(DCC)是一种新的近净尺寸的陶瓷成型技术;但湿坯强度较低(与注凝成型和注射成型相比).为了提高Al_2O_3直接凝固成型后的坯体强度,在Al_2O_3-DCC过程中引入AlOOH本文系统考察了Al_2O_3+AlOOH体系的电动特性、流变性及凝固过程.重点讨论了AlOOH加入对体系凝固行为,如活性酶添加量、固化过程动力学的影响. 相似文献
6.
Al_2O_3/Al复合材料型内处理成型工艺研究 总被引:4,自引:0,他引:4
论述了Al2O3(p)/Al复合材料型内处理成型工艺,并讨论了影响复合区域凝固过程的有关因素,指出了控制复合区域内Al2O3粒子的分布的途径。 相似文献
7.
8.
9.
10.
11.
The coagulation cascade is now recognized to be a series of proteolytic events mainly localized to the surface of activated platelets. Once platelets become activated by exposure to activated endothelium, they release mediators such as P-selectin and von Willebrand factor that promote microvesicle formation and platelet adherence. The microvesicles fuse with the activated platelet membrane, providing tissue factor and its ligand, factor VIIa. Clotting factors bind to adjacent receptors on the membrane, enabling the cascading proteolytic cleavages of zymogens to active enzymes, culminating in thrombin generation. Fibrin formation thus occurs in the sheltered environment of the platelet membrane, where it is localized to the site of injury and protected from circulating inhibitors. 相似文献
12.
David Green 《Hemodialysis international. International Symposium on Home Hemodialysis》2001,5(1):70-73
The endothelium is the principal anti‐thrombotic mechanism, providing a non wettable surface and generating potent vasodilators (nitric oxide and prostacyclin) and clotting inhibitors [thrombomodulin and tissue factor pathway inhibitor (TFPI)]. When the integrity of the endothelium is breached, vasoconstriction occurs through neural and chemical (endothelin, thromboxane) mechanisms, and platelet adhesion is facilitated (von Willebrand factor). Activation of platelets accompanied by microparticle formation provides a thrombogenic surface for subsequent coagulation reactions. The initial generation of small amounts of thrombin greatly amplifies subsequent clotting factor activation and results in substantial thrombin formation. Thrombin activates an inhibitor of fibrinolysis [thrombin activatable fibrinolysis inhibitor (TAFI)] which prevents the binding of plasminogen to fibrin. Mechanisms to limit clot formation include inhibition of the tissue factor–factor VIIa complex by TFPI, inhibition of activated factors V and VIII by activated protein C, and binding of thrombin by thrombomodulin, heparin cofactor II, and anti‐thrombin. Clot dissolution is promoted by plasminogen activators (tissue plasminogen activator and urokinase) and by plasminogen. 相似文献
13.
直接凝固注模成型技术 总被引:15,自引:0,他引:15
直接凝固注模成型是瑞士苏黎世联邦高等工业学院L.J.Gauckler实验室发明的一项新的成型技术,具有素坯密度高、密度均匀、坯体收缩和形变极小等优点,特别适用于大尺寸、复杂形状的陶瓷部件的成型,有广阔的应用前景.本文着重介绍了直接凝固注模成型的基本原理和技术关键. 相似文献
14.
Coagulation and electrocoagulation of oil-in-water emulsions 总被引:2,自引:0,他引:2
Cañizares P Martínez F Jiménez C Sáez C Rodrigo MA 《Journal of hazardous materials》2008,151(1):44-51
In this work the efficiencies of the chemical and the electrochemical break-up of oil-in-water (O/W) emulsions with hydrolyzing aluminium salts are compared. It has been obtained that the efficiency of the processes does not depend directly on the dosing technology, but on the total concentration of aluminium and pH. This latter parameter changes in a different way in the chemical and the electrochemical processes: the pH increases during the electrochemical experiments since the electrochemical system leads to the formation of aluminum hydroxide as a net final product, but it decreases in the conventional ones due to the acid properties of the aluminum salts added (AlCl3 or Al2(SO4)3). The break-up of the emulsions only takes place in the range of pHs between 5 and 9, and the amount of aluminium necessary to produce the destabilization of the emulsion is proportional to the oil concentration. Electrolytes containing chlorides improve COD removal as compared with those containing sulphate ions. Aluminium hydroxide precipitates were found to be the primary species present in solution in the conditions in which the breaking process is favoured. Consequently, the attachment of more than one droplet of oil at a time to a charged precipitate-particle (bridging flocculation) was proposed as the primary destabilization mechanism. 相似文献
15.
综述了直接凝固注模成型技术的反应机理及其工艺流程,概括出悬浮体系凝固中影响凝固动力学的因素,并对当前国内外在该技术上的研究现状作了总结性介绍,讨论了直接凝固注模成型技术的主要研究问题及发展前景。 相似文献
16.
Jonathan A.D. Wattis D. Graham McCartney Throstur Gudmundsson 《Journal of Engineering Mathematics》2004,49(2):113-131
Models for coagulation with mass loss arising, for example, from industrial processes in which growing inclusions are lost from the melt by colliding with the wall of the vessel are derived and solved. A variety of loss laws and a variety of coagulation kernels are considered, exact results derived where possible, and more generally the equations are reduced and solved by similarity solutions valid in the large-time limit. One notable result is the effect that mass removal has on gelation: for small loss rates, gelation is delayed, whilst above a critical threshold, gelation is completely prevented. Finally, by forming an exact explicit solution for a more general initial cluster-size distribution function, it is shown how numerical results from earlier work can be interpreted in the light of the theory presented herein. 相似文献
17.
18.
直接凝固注模成型SiC陶瓷——浆料凝固过程的研究 总被引:6,自引:1,他引:5
直接凝固注模成型是一种新的(准)净尺寸成型陶瓷部件的方法,本文主要研究了此方法的关键步骤一浆料凝固过程,高固相含量(>55vol%)浆料从可浇注的低粘度状态转变为有一定强度的凝固态(坯体)主要有两种方法,即增加浆料中的电解质浓度和移动浆料的pH值至等电点。 相似文献
19.
直接凝固注模成型氮化硅陶瓷 总被引:7,自引:0,他引:7
直接凝固注模成型是一种新颖的原位凝固成型工艺,特别适合于复杂形状陶瓷部件的成型.通过粉体的表面改性、浆料pH值的调节以及引入高效分散剂等途径制备出了低粘度高固含量的氮化硅浆料,通过直接凝固注模成型可以获得适当的素坯密度和强度.坯体气孔分布均匀,为较窄的单峰分布,断口光滑平整,坯体各部位密度具有很好的均匀性.在相对较低的烧结温度下(1750℃),成型坯体经过无压烧结可达到理论密度的98%,基本实现致密化.烧结体结构均匀,晶粒均匀生长,发育良好.经1800℃烧结2h后,抗折强度达758.4 MPa,断裂韧性为6.3MPa·m1/2. 相似文献