摘要:
A low expansion ceramic material has a composition represented by the molecular formula i (Na) j (Zr.sub.2-z Na.sub.4z) k (P.sub.3-x Na.sub.x Si.sub.x)O.sub.12 in which the molar proportions i, j and k are each within the range from about 0.9 to about 1.1, and i+j+k equal 3; and, for molar proportions i, j and k each equal to 1.0, the ceramic composition falls within the area defined by the points A, B, C and D in a quarternary diagram of SiO.sub.2, Na.sub.2 O, P.sub.2 O.sub.5 and ZrO.sub.2, the coordinates of the points being:A: x=0.2, z=0B: x=0.6, z=0C: x=0, z=0.25D: x=0, z=0.125The ceramic material is especially suitable as a substrate for optically reflecting films.
摘要:
Compositionally triphasic nanocomposite gel is made by mixing two or more sols of ceramic precursor oxides. Such gel is then dried and ground to a fine powder which is pressed into compact bodies. The compact bodies are thereafter fired in a sintering oven at from 1100.degree. C. to 1400.degree. C. and, aided by the heat of reaction of the two or more nono gel powders, the (heterogeneous) mixture of such powders crystallizes into a homogeneous crystalline ceramic of .alpha.-cordierite at up to 100% of theoretical density. Thus, novel method of manufacture and novel ceramic end-product are provided.
摘要:
Ceramic oxide diphasic xerogels of structurally dissimilar phases (crystalline and amorphous, semicrystalline or noncrystalline) but compositionally similar phases will be converted to crystalline ceramic oxide products having enhanced densification when subjected to substantially lower sintering temperature.
摘要:
The present disclosure is directed to a method of converting green particles to form finished particles. The apparatus used for sintering incorporates an elongate hollow tube, an insulative sleeve there about to define an elevated temperature zone, and a microwave generator coupled through a wave guide into a microwave cavity incorporated the tube. The particles are moved through the tube at a controlled rate to assure adequate exposure to the microwave radiation. Another form sintered a solid part in a cavity or mold.
摘要:
Multimode and single mode microwave energy is used to improve the extraction of metals from chalcogenide minerals. In one process microwave energy is used to comminute the mineral after which the mineral is reacted with acid in the presence of microwave energy. Following treatment the mineral is removed and the extracted metal is recovered from the acid. In another process chalcogenide minerals are exposed to the magnetic field maximum or the electrical field maximum of a single mode electromagnetic energy. This treatment causes a phase separation between metals and silicates within the mineral leaving metal rich regions from which the metal can be readily recovered by traditional methods.
摘要:
An apparatus (10) for the development of transparent alumina ceramics using microwave energy at the frequency between 0.915 and 2.45 GHz inclusive in hydrogen atmosphere at ambient pressure comprises an enclosed, insulated chamber (14) to retain a workpiece (12) for the application of microwave energy. The chamber comprises a TE103 single mode or a multimode microwave cavity into which is mounted a quartz tube (18). An insulation material (20), transparent to microwave energy, is positioned within the quartz tube. A port (28) for the introduction of hydrogen penetrates the cavity so that the microwave sintering of the workpiece is performed in an ultra-pure hydrogen atmosphere. The workpiece is preferably mounted on a refractory ceramic such as alumina tube for the microwave sintering process. A method, preferably using the apparatus, develops transparent alumina ceramics and single crystal sapphire.
摘要:
This disclosure sets forth a method and apparatus for microwave processing of green work pieces. Typically, individual green work pieces are formed in a small mold cavity crucible, and individual crucibles are then indexed into and out of a tube for a controlled transit time along the tube. The tube extends in one embodiment through a preheater and then into the microwave cavity, the preheater providing an initial heating step to change the rate of absorption of microwave energy so that microwave sintering is accomplished in the cavity.
摘要:
A low expansion ceramic composition is represented by the formula Ca.sub.0.5 Ti.sub.2 P.sub.3 O.sub.12 in which up to 100 percent of the Ca is replaced by one or more of the other alkaline earth metals and alkali metals, the alkali metals being selected from the group consisting of Na, Li, K and combinations thereof and substituted in the ratio of two units of alkali metal for each unit of Ca replaced. Up to 100 percent of the Ti is replaced by one or more members selected from the group consisting of Zr, Sn, Nb, Ta and Cr. For each unit of Cr replacement an approximately equal unit of alkali metal is added. For each unit of Nb and/or Ta replacement an approximately equal unit of Na and/or K replaces a unit of Ca. Up to 100 percent of the P may be replaced by Si and/or S. The total of the amounts of Ca, other alkaline earth metals, Li, K, Ti, Sn, Nb, Ta and Cr is greater then zero. Preferably up to 100 percent of the Ca is replaced by Na, and up to 100 percent of the Ti is replaced by Zr or NaCr. The ceramic composition is especially suitable for optically reflecting films.
摘要翻译:低膨胀陶瓷组合物由式Ca 0.5 Ti 2 P 3 O 12表示,其中至多100%的Ca被一种或多种其它碱土金属和碱金属代替,碱金属选自Na, Li,K及其组合,并以每单位Ca取代的两单位碱金属的比例进行取代。 高达100%的Ti被选自由Zr,Sn,Nb,Ta和Cr组成的组中的一种或多种所取代。 对于每个单位的Cr替换,添加大约相等的碱金属单位。 对于Nb和/或Ta替代的每个单位,大约相等单位的Na和/或K代替Ca的单位。 高达100%的P可被Si和/或S替代.Ca,其他碱土金属,Li,K,Ti,Sn,Nb,Ta和Cr的量的总和大于零。 优选高达100%的Ca被Na替代,并且至多100%的Ti被Zr或NaCr代替。 陶瓷组合物特别适用于光反射膜。
摘要:
A method for changing the color of a diamond. The method comprises placing the diamond in a substrate holder in a chemical vapor deposition (CVD) equipment. The CVD equipment is maintained at pressures near or below atmospheric pressure. A mixture of gases including hydrogen is introduced inside the CVD equipment. The introduced mixture of gases is energized by using microwave radiation to heat the diamond to temperatures above 1400° C. Then, the diamond is maintained at temperatures above 1400° C. for few seconds to few hours.