摘要:
Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.
摘要:
Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.
摘要:
Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.
摘要:
A transition metal carbide is formed from a precursor mixture comprising at least one of the group consisting of: a transition metal, a transition metal carbide and a transition metal oxide. The precursor mixture may contain the desired transition metal carbide (e.g., WC), but if the desired transition metal carbide is present in the precursor mixture, there is necessarily a significant amount of another compound such as a transition metal oxide, undesired carbide (e.g., W2C) or transition metal. The method involves forming an admixture by mixing the precursor mixture with a sufficient amount of carbon to carburize the precursor mixture to the transition metal carbide and reacting the admixture in an inert or reducing atmosphere at a temperature for a time sufficient to convert the admixture to the transition metal carbide, wherein the admixture is reacted in the presence of a means to enhance transfer of heat into the admixture, an inert or reducing gas flowing through at least a portion of the admixture or combination thereof.
摘要:
Ceramic precursor materials bound together by a product of a condensation reaction between a first reactant that has at least one reactive hydroxyl moiety, such as a carbohydrate, and a second reactant that has at least one reactive nitrogen-containing moiety, such as melamine, and dried or dried and calcined, form porous aggregates that resist crushing or disintegration during processing through various reactor apparatus.
摘要:
Hard disk drive components, such as, sliders, load beams, support arms, actuators, actuator bearings, spacers, clamps, spindles, ball bearings, thrust bearings, journal bearings, base plates, housings, and covers, formed of a multi-phase ceramic-based material. One method of making the hard disk drive components includes (a) forming a porous body of ceramic; (b) infiltrating a liquid into the pores of the ceramic body; (c) solidifying the infiltrated liquid; and (d) machining the metal-infiltrated ceramic body to form the hard disk drive component.
摘要:
A hard drive disk substrate is formed of a multi-phase ceramic-based material having at least two phases with amorphous phases being present in an amount less than about 1 volume percent based on the volume of the ceramic-based material or at least one phase being free metal. A process for producing the ceramic-based disk substrate is produced by forming a flat disk of a porous ceramic and then infiltrating the porous ceramic with a metal whereby a multi-phase ceramic-based computer hard drive disk is produced. Additionally, a step of passivating the porous ceramic by elevating it to a temperature of about 1300.degree. to about 1800.degree. C. before the infiltrating step may be performed, such that the surfaces are passivated and the reaction kinetics can be controlled during the infiltrating step. A preferred composite material is made of a multi-phase boron carbide composite material including grains having peaks with an average roughness value, Ra, of between about 1 to about 200.ANG., the roughness value being formed in situ by causing a micro hardness gradient of between about 19 and about 3200 Kg/mm.sup.2 in the various phases of the multi-phase boron carbide composite material.
摘要翻译:硬盘驱动器盘基板由具有至少两相的多相陶瓷基材料形成,其中无定形相以基于陶瓷基材料的体积或至少一相的量存在的量小于约1体积% 是免费金属。 通过形成多孔陶瓷的平板,然后用金属渗透多孔陶瓷来制造陶瓷基盘基板的方法,由此制造多相陶瓷基计算机硬盘驱动盘。 此外,可以在渗透步骤之前将其升高至约1300℃至约1800℃的温度来钝化多孔陶瓷的步骤,使得表面被钝化,并且可以在渗透步骤期间控制反应动力学 。 优选的复合材料由多相碳化硼复合材料制成,其包括具有平均粗糙度值Ra的峰值在约1至约200之间的晶粒,该粗糙度值通过使原位形成的微观硬度梯度 在多相碳化硼复合材料的各个相中约19至约3200Kg / mm 2。
摘要:
A silicon nitride-based powder composition that yields sintered bodies having a density of at least 3.15 g/cm.sup.3 by pressureless sintering. The composition includes silicon nitride and an amount of bismuth oxide as a phase transition aid in addition to magnesium oxide, aluminum oxide, zirconium oxide and, optionally, silicon dioxide. The sintered bodies can be produced at temperatures of 1650.degree. C. or less.
摘要翻译:一种氮化硅基粉末组合物,其通过无压烧结得到密度为至少3.15g / cm 3的烧结体。 除了氧化镁,氧化铝,氧化锆和任选的二氧化硅之外,组合物包括氮化硅和一定量的作为相转移助剂的氧化铋。 烧结体可以在1650℃或更低的温度下生产。
摘要:
A hard drive disk substrate is formed of a multi-phase ceramic-based material having at least two phases with amorphous phases being present in an amount less than about 1 volume percent based on the volume of the ceramic-based material or at least one phase being free metal. A process for producing the ceramic-based disk substrate is produced by forming a flat disk of a porous ceramic and then infiltrating the porous ceramic with a metal whereby a multi-phase ceramic-based computer hard drive disk is produced. Additionally, a step of passivating the porous ceramic by elevating it to a temperature of about 1300.degree. to about 1800.degree. C. before the infiltrating step may be performed, such that the surfaces are passivated and the reaction kinetics can be controlled during the infiltrating step. A preferred composite material is made of a multi-phase boron carbide composite material including grains having peaks with an average roughness value, Ra, of between about 1 to about 200 .ANG., the roughness value being formed in situ by causing a micro hardness gradient of between about 19 and about 3200 Kg/mm.sup.2 in the various phases of the multi-phase boron carbide composite material.
摘要翻译:硬盘驱动器盘基板由具有至少两相的多相陶瓷基材料形成,其中无定形相以基于陶瓷基材料的体积或至少一相的量存在的量小于约1体积% 是免费金属。 通过形成多孔陶瓷的平板,然后用金属渗透多孔陶瓷来制造陶瓷基盘基板的方法,由此制造多相陶瓷基计算机硬盘驱动盘。 此外,可以在渗透步骤之前将其升高至约1300℃至约1800℃的温度来钝化多孔陶瓷的步骤,使得表面被钝化,并且可以在渗透步骤期间控制反应动力学 。 优选的复合材料由多相碳化硼复合材料制成,其包括具有平均粗糙度值Ra的峰值在约1至约200之间的晶粒,该粗糙度值通过使原位形成的微观硬度梯度 在多相碳化硼复合材料的各个相中约19至约3200Kg / mm 2。