Composite powders preparation

G.J.C. Carpenter, Z.S. Wronski, NanocrystaUine NiO and NiO-Ni(OH) composite powders prepared by thermal and mechanical dehydroxylation of nickel hydroxide, Nanostructured Mater. 11(1) (1999) 67-80. 

Itatani, K., Akiyama, K., Aizawa, M., Scott Howell, F., Okada, I. Sinterability of apatite-zirconia composite powder prepared by ultrasonic spray freeze-drying technique. J. Soc. Inorg. Mater. Jpn. 286,194-202, 2000... 

G. J. C. Carpenter, Z. S. Wronski, Nanocrystalline NiO and NiO-Ni(OH)2 Composite Powders prepared by Thermal and Mechanical Dehydroxylation of Nickel Hydroxide, Nanostructured Mater., 1999,... 

Composite powder prepared by an in situ sol method using SiOj beads as grinding media... 

Fig. 8 Time dependence of the degree of swelling of Highvis/Loponite composite powder prepared at the optimum condition (O) and hydrophilic polymer, Aquaric ( ), in water.

Deb, A., Chatterjee, P. and Sen Gupta, S.P. (2007) Synthesis and microstructural characterization of a-Al203 t-Zr02 composite powders prepared by combustion technique. Materials Science and Engineering A, 459,124—31. 

The zeolites-chitosan composites were prepared by adding a known amount of zeolite (X, Y, or mordenite) into a 3 % chitosan solution in 1 % aqueous acetic acid. The zeolite powder was dispersed in the chitosan solution and stirred at room temperature during 1-2 hours. The gelling procedures were later carried out like as in the absence of zeolites. 

When a trihydrate of an identical composition was prepared by grinding in a ball mill with water181), the powder showed only one X-ray line near 3 angstroms, in contrast to the crystalline tobermorite which had two strong lines in this region. 

In the field of metallic powder applications, a method of plasma spray coating suitable for biomedical materials has been developed using titanium and calcium phosphate composite powder. By means of the mechanical shock process, the appropriate composite powder was prepared, and plasma sprayed on Ti substrate under a low-pressure argon atmosphere. A porous Ti coating layer was obtained in which the surface and the inside of the pores were covered thinly with hydroxyapatite. This surface coating is expected to show excellent bone ingrowth and fixation with bone (21). 

Upon comparing the composition of the powders prepared in different countries for fire-arms, they will be found to agree move or Ieti3 closely with the cci>-... 

Figure 1. Powder XRD diagrams of mesostructured alumi nophosphate / surfactant composite materials prepared in (a) water (120°C), (b) ethanol (90°C), (c) methanol (25°C), (d) ethanol (10°C). Lamellar and hexagonal phases are indexed "4" corresponds to a phase with presumably lamellar structure.

Beside the production of pure Si3N4, the gas phase processes are used for the preparation of Si3N4/SiC composite powders used for nanocomposite materials [210, 222, 223]. For the production of such complex powders different kinds of evaporable Si organic compounds are used, e.g., hexamethyldisilazane. 

The third way to prepare CNT-ceramic composite powders is via the synthesis of CNT by a CCVD process, in situ in the ceramic powder. A ceramic powder which contains catalytic metal particles at a nanometric size, appropriate to the formation of CNTs, is treated at a high temperature (600-1100°C), in an atmosphere containing a hydrocarbon or CO. In the method reported in 1997 by the present authors,27 iron nanoparticles are generated in the reactor itself, at a high temperature (>800°C), by the selective reduction in H2/CH4 (18% CH4) of an a-Al203 based oxide solid solution ... 

Sologub et al. (1994) investigated by X-ray powder diffraction the alloy with the nominal composition Y25Ni25Sb5o prepared by arc melting ingots of the elements in argon and annealed at 870 K in evacuated quartz tubes for 2 weeks and quenched in water. The sample was found to consist of two phases, namely NiSb (NiAs type, a = 0.3926, c = 0.5134) and YSb (NaCl type, a = 0.61707). The materials used were Y 99.9 wt.%, Ni 99.9 wt.% and Sb 99.9 wt.%. 

The salt monomer method was successfully applied to the preparation of the electrically-conducting polyimide-carbon black composites [62]. The composites are prepared as follows An aqueous solution of salt monomer 9PMA was mixed with carbon black, giving a suspension. This was evaporated to dryness under reduced pressure to afford a homogeneously-mixed powder composed of the salt monomer and carbon black. The powder was subjected to solid-state thermal polycondensation in the form of a pellet at 240 °C for 1 h under atmospheric pressure. The semiconducting aliphatic polyimides (P-9PM, Tm=315 °C) having electric conductivity of about 10"6 S/cm was readily obtained by mixing only 1 wt% of carbon black based on the polyimide. 

Bilgrien CJ et al. (1992) Storage-stable flowable organosiloxane composition powders and their preparation. US Patent 5 153238... 

Composition An extruded powder prepared from two types of nitrocellulose, blended to give average nitrogen content of 13.15 per cent and a solubility in ether-alcohol of 40 per cent or greater. Components Pyro-cotton, 12.6 0.1 per cent Guncotton, 13.2 per cent or greater. 

The double microemulsion-mediated process also provides a convenient method for preparing a metal-containing sihcate coating. The two microemulsion systems contained two common components anionic sirrfactant AOT and cyclohexane [134]. The difference was that the first microemulsion consisted of an aqueous solution of sodiirm metasihcate (0.2 M) and 10 wt% SDS as the co-surfactant, while the second microemulsion consisted of an aqueous solution of copper nitrate (0.1 M) and 10 wt% SDS. The copper-ion microemulsion was added to the silicate-ion microemulsion with constant stirring. After 8 h of gel-lation, and ageing for an additional 24 h, copper nitrate crystals were identified within the sihcate network. SUica-copper composite powders with various copper contents (4-20 wt%) and surface areas of 200-400 m /g were synthesized. 

Li et al. developed a solid-state reaction process to synthesize perov-skite-type LaCoOs NCs with grain diameters of 15 0 run (Li et al., 2002). In the first step of the preparation, 5 run composite hydroxide NPs were s)mthesized by grinding metal nitrates liquid paste and mixing with KOH. Then the composite powders were calcined at 800 °C, yielding a single-phase oxide. Tien-Thao et al. prepared LaCo Cui J.O3 x < 0.3) by mechano-synthesis (Tien-Thao et al., 2008). The sample has various distinct Co " " ions in the perovskite lattice, which are more reducible. The reduced catalyst surface comprising cobalt and copper atoms is very selective for the hydrogenation of CO. 

Dezanneau et al. reported Lai cMn03+a nanocrystalline powders prepared by an acylamide polymerization sol-gel method (Dezanneau et al., 2002a,b, 2003). The composition analysis revealed that for La/ Mn < 0.9 the Mna04 phase was present, while for La/Mn > 0.9, the high oxygen excess led to considerable vancancies on cationic sites. The Curie temperature remained constant at 295 K for the former case, while decreased Curie temperatures were observed for the latter case, due to the increasing amoimt of Mn vacancies. 

All the monolith composites were prepared at a 1 1 ratio between the magnesium silicate clay binder and the AC or alumina. After premixing of the dry powders by careful addition of water a dough was formed. This dough was extruded as honeycomb monolithic structures with parallel channels of square section at a cell density of 8 cells cm and a wall thickness of 0.9 mm using a Bonnot single screw extruder. 

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