摘要:
In a thermoelectric generator or Peltier arrangement having a thermoelectrically active semiconductor material constituted by a plurality of metals or metal oxides the thermoelectrically active material is selected from a p- or n-doped semiconductor material constituted by a ternary compound of the general formula (I) MexSAySBz (I) with Me=Al, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu or Ag, SA, SB=B, C, Si, Ge, Sb, Se or Te, where SA and SB respectively come from different groups of the periodic table, x, y, z independently of one another have values from 0.01 to 1, and where the proportion by weight of SA and SB together is no more than 30%, expressed in terms of the total semiconductor material, except for ternary compounds constituted by AlB12 and SiB6, or a mixed oxide of the general formula (II) [ ( CaO ) u · ( SrO ) v · ( BaO ) w · ( 1 / 2 Bi 2 O 3 ) x ] f · 2 n + a 2 · ( { k } Me n O n 2 · { 2 - k } Me n + a O n + a 2 ) ( II ) with Me=Fe, Cu, V, Mn, Sn, Ti, Mo, W n=integer from 1 to 6, a=1 or 2, f=number from 0.2 to 5, k=number from 0,01 to 2, u+v+w+x=1.
摘要:
A mixture Ia comprises a mix IIa composed of a) from 1 to 95% by weight of a solid III, preferably a basic solid III, with a primary particle size of from 5 nm to 20 &mgr;m and b) from 5 to 99% by weight of a polymeric composition IV, obtainable by polymerizing b1) from 5 to 100% by weight, based on the composition IV, of a condensation product V of &agr;) at least one compound VI which is capable of reacting with a carboxylic acid or with a sulfonic acid or with a derivative or a iixture of two or more of these, and &bgr;) at least 1 mol per mole of the compound VI of a carboxylic acid or sulfonic acid VII which has at least one functional group capable of free-radical polymerization, or of a derivative thereof or of a mixture of two or more thereof and b2) from 0 to 95% by weight, based on the composition IV, of another compound VIII with an average molecular weight (number average) of at least 5000 having polyether segments in its main or side chain and at least one ester of the formula (E1) to (E5) where each of R1, R2, R3 and R4 is identical with or different from the others and, independently of the others, is linear or branched-chain C1-C4-alkyl (—CH2—CH2—O)n—CH3, where n is from 1 to 3, C3-C6-cycloalkyl or an aromatic hydrocarbon group which may in turn be substituted, with the proviso that at least one of the groups R1, R2, R3 or R4 is (—CH2—CH2—O)n—CH3, where n is from 1 to 3.
摘要:
A process for preparing alkanesulfonic acids from dialkyl sulfites comprises the following steps: rearrangement of dialkyl sulfite in the presence of a suitable catalyst to form the corresponding alkyl alkanesulfonate and hydrolysis of the resulting alkyl alkanesulfonate to give the corresponding alkanesulfonic acid.
摘要:
The molding composition contains, in a flowable binder, from 20 to 50% by vol., based on the total volume of the molding composition, of a powder comprising one or more metal oxides and, if desired, metal carbides and/or metal nitrides which cannot be reduced using hydrogen, where at least 65% by vol. of the powder has a maximum particle size of 0.5 .mu.m and the remainder of the powder has a maximum particle size of 1 .mu.m, and at least 90% by vol. of the powder comprises metal oxides which can be reduced using hydrogen. The metal oxides which can be reduced using hydrogen are Fe.sub.2 O.sub.3, FeO, Fe.sub.3 O.sub.4, NiO, CoO, Co.sub.3 O.sub.4, CuO, Cu.sub.2 O, Ag.sub.2 O, Bi.sub.2 O.sub.3, WO.sub.3, MoO.sub.3, SnO, SnO.sub.2, CdO, PbO, Pb.sub.3 O.sub.4, PbO.sub.2 or Cr.sub.2 O.sub.3, or mixtures thereof.
摘要:
The production of open-celled porous inorganic sintered products comprises the stepsa) introducing a flowable mixture comprising an aqueous polymer dispersion, sinterable inorganic powder and dispersant into a precipitation bath in which the polymer precipitates or coagulates to form a non-flowable product comprising polymer, inorganic powder and dispersant,b) removing the product from the precipitation bath and drying the product,c) heating the product to remove polymer and dispersant and sintering the product.The porous open-celled sintered products comprising sintered inorganic powder have a pore volume of from 50 to 95%, a surface area of from 0.1 to 50 m.sup.2 /g and an at least bimodal pore size distribution having maxima in the ranges from 0.02 to 5 .mu.m and from 20 to 500 .mu.m.
摘要:
The preferred sintered parts made of oxygen-sensitive, non-reducible powders and their production by injection-molding are distinguished by the powders used being freed of their oxide layer by attritor milling in a water-free organic solvent, in the presence or absence of an additional reductant, the oxide particles being removed if necessary by filtration or screening in the presence of the organic solvent, the oxide-free powder being mixed as suspension with a polyacetal as binder under a protective gas, the organic solvent being distilled off, the mixture of powder and polyacetal being heated above the melting point of the polyacetal and being compounded to give a homogeneous composition, the granular material thus obtained being processed in an injection-molding machine made inert with argon to give shaped bodies, the shaped bodies being freed of binder under the action of oxalic acid in a closed ceramic container which nevertheless allows pressure equilibration under protective gas at atmospheric pressure or reduced pressure, the shaped bodies being, after binder removal, transferred in their container without contact with air into a sintering furnace and being sintered therein according to the prior art.
摘要:
In a process for injection molding foamed parts of polylactide, the polylactide melt contains solvent and cools to below the melting point during the expansion in the mold and is expanded in the temperature range between the glass softening point and the melting point.
摘要:
The invention relates to foamed polylactide articles obtainable by foaming a mixture of amorphous polylactide granules which contain a blowing agent and of a finely divided polylactide which does not contain a blowing agent, and to a process for producing same.
摘要:
Polymers contain, as mesogenic groups, groups which produce a discotic phase, and furthermore can control pleochroic dyes.The novel polymers possess novel properties, and combination of properties, which the conventional polymers which form liquid-crystalline phases do not possess.The polymers can be used in electro-optical displays, in storage elements, as electrically or photo-electrically conductive polymers and as strain sensors.
摘要:
In the preparation of compact, crystalline and pore-free moldings from an oxide ceramic, amorphous oxide powders of beryllium, magnesium, aluminum, boron, zirconium, thorium or silicon or mixed oxides of silicon with these elements, in which some of the oxygen is replaced by bound nitrogen, are used as starting materials. These amorphous oxide powders containing bound nitrogen are compressed in a first stage at above the glass transition temperature but below the crystallization temperature to give a glassy molding, and the latter is then heated in a second stage to above the crystallization temperature. In the case of the individual oxides, from 5 to 30% of the oxygen are replaced by bound nitrogen, and in the case of the mixed oxides of silicon with these elements from 50 to 90% of the oxygen are replaced by bound nitrogen.