Powder oxidation

The plasma chemical decomposition method is based on rapid heating, decomposition and hydrolysis of fluoride compounds to obtain powdered oxides following interaction with water. Rakov and Teslenko [533] showed that the following hydrolysis equilibrium... 

Epoxy-polyamide resin with a powdered oxide filler... 

Several toxic effects of inorganic oxides become evident when oxides are inhaled in a finely powdered form. A high concn of powdered oxides can lead to asphyxiation on short exposure or lung cancer at somewhat lower concns if the exposure occurs over a prolonged period. 

Photo flash powders are loose mixts of powdered oxidizers such as Ba nitrate and K perchlorates with metallic fuels, principally Mg, A1 and Zr. These ingredients have such small particle sizes that they bum with expl violence for durations of less than 0.1 sec. At present photoflash powders are used exclusively in military aerial photography, whereas civilian applications are served by electrically ignited Zr or Hf wire containing flashbulbs. Since 1970. non-electric, pyrotechnically functioned, flash cubes have appeared on the market (USPs 3535063,3540813 3674411)... 

The powdered oxidant functions as an explosive when mixed with finely divided metals, organic materials or sulfur, which increase the shock-sensitivity up to that of picric acid [1]. The hazardous properties of such mixtures increase as the particle size of the oxidant salt decreases [2],... 

Crozier, T. H., HMInsp. Expl. Spec. Rept. 237, London, HMSO, 1929 A 20 t quantity of an incendiary bomb mixture of the finely powdered oxide, aluminium and sulfur became accidentally ignited and burned with almost explosive violence. It is similar to thermite mixture. 

Action of chlorine trifluoride causes incandescence [1]. Manganese dioxide catalytically decomposes powerful oxidising agents, often violently. Dropped into cone, hydrogen peroxide, the powdered oxide may cause explosion [2], Either the massive or the powdered oxide explosively decomposes 92% peroxomonosulfuric acid [3], and mixtures with chlorates ( oxygen mixture , heated to generate the gas) may react with explosive violence [4], Cuban pyrolusite can be used in place of potassium dichromate to promote thermal decomposition of potassium chlorate in match-head formulations [5],... 

In addition to water atomization, oil atomization using various hydrocarbons (oils) is the only other liquid atomization process used in the atomization of liquid metals. Due to the similarity of these two atomization processes, water atomizers can be readily adapted to oil atomization. Some problems inherent in water atomization, such as powder oxidation, can be avoided in oil atomization. The cost-effectiveness is superior to gas atomization, but not as good as water atomization. 

In Preparation 3-8, use is made of a reagent containing 94 % lead tetraacetate and 6 % acetic acid. If the dry, powdered oxidizing agent is used, the reaction solution must be cooled to —40°C or lower before its addition if comparable results are to be obtained. Yields are definitely reduced if the reaction time is prolonged much beyond 10 sec, and if the steam distillation is not completed within a very short time. For this reason this preparation is probably suitable only if small quantities of product are desired. Yields vary from modest to good for the preparation of nitrosobenzene, p-nitrosotoluene, and p-nitroso-chlorobenzene. An attempt to prepare nitrosocyclohexane by this method did not lead to identifiable products. 

The principal Zn ores are Zn blende (Zn sulfide, sphalerite) and calamine (Zn carbonate, smithsonite), both of which can be converted into the oxide by roasting. The volatility of Zn at bright red heat enables the metal to be extracted from the ore by distln. Toward this end the powdered oxide is mixed with a stoichiometric excess of anthracite and heated to 1200— 1300° in a retort causing the Zn oxide to be reduced ... 

A series of runs was made in which the uptakes of the radioactive oxide vapors by samples of single, unmelted oxides were measured. This was done to obtain some information on the relative reactivity of the oxide vapors with various simple oxides. The partial pressures of the oxide vapor and the sample temperature (1400°C.) were held constant. All oxide samples used had melting points in excess of 1400°C. The samples were prepared by pressing the powdered oxides (Reagent grade) into pellets 0.62 cm. in diameter and about 0.05 to 0.08 cm. thick. The... 

Mixt of NC 46.5, NG (or DEGDN) 33.5, PETN (or RDX) 16, St w-insol soap 4% is blended under w and centrifuged to lower the w-content to ca 30%. The soap consists of Caoleate 88, Mg stearate 10 St A1 stearate 2%. The blend is then treated as in Example 1A, but not to complete removal of w. Then, in the middle of rolling operation, some powdered oxidizer (such as Amm or K perchlorate) is incorporated and the material is continued to be rolled to completion of dehydration and gelatinization. The amt of oxidizer is 5 to 45% of dried sheet Example 3 ... 

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