Translation of "Voroxidation" in English

Additional known measures are, e.g. pre-oxidizing or oxinitriding.

This pre-oxidation is necessary in the case of solid Mo and W samples.

During pre-oxidation, therefore, activity is not removed from the systems to be decontaminated.

According to this example, in zone I, a preoxidation step of the highly reactive initial carbon black is conducted.

In certain types of alloy steels a preoxidation is performed in order to achieve a uniform result of treatment.

A pre-oxidation must in particular be carried out, if the conditions of use do not trigger any sufficient oxidation.

Hitherto it was possible to obtain fibers having a similar, low, weight loss only by means of a separate pre-oxidation, of the type known for preparing carbon fibers.

This usually very time-consuming and expensive pre-oxidation cannot be combined with the production process for the starting filaments so as to give one continuous process.

More recently Japanese Published Application No. 51-90,387 described aftertreating of moldings with copper(I) salts to catalyze the pre-oxidation when thermostabilizing these products.

There was thus still the unsolved object of preparing in a simple, continuous manner, from organic polymers, filaments and fibers which have the same, or even better, properties as the filaments obtained by lengthy pre-oxidation.

This subsequent treatment can be performed by known methods and generally includes a pre-oxidation, and subsequent carbonization and in some cases graphitization.

With an increasing amount of hydrogen peroxide in the preoxidation step, the yield of quinolinic acid rises until it reaches a maximum with 51 to 52%, relative to the quinoline used, at 80% of the stoichiometrically required quantity of hydrogen peroxide.

The thus produced pitch with 85-100 percent mesophase fraction is very well suitable for a melt spinning and, after preoxidation and carbonization or graphitization, to produce carbon fibers or graphite fibers of high strength and modulus values.

After acidic preoxidation, as well, better decontamination results are obtained than with oxalic acid; this is carried out, for instance, with tartronic acid, mesoxalic acid and dihydroxytartaric acid.

A particularly good outcome of decontamination is attained, for instance, after alkaline preoxidation, with a ketonic acid or a hydroxycarbonic acid, if this acid is combined with a pyridine carbonic acid as a complexing agent.

It is assumed that in the preoxidation reaction step, an activation and/or splitting of the aromatic ring takes place, and in the second oxidation stage a targeted oxidation of the activated products into quinolinic acid takes place.

The gas which moves from zone II up into zone I is already largely free of oxygen content, i.e. it is an oxygen poor gas, and therefore for the preoxidation step of the carbon black, there is introduced at the lower end of zone I additional air through tangentially oriented introduction lines.

It is known, in steam activation, to subject crude materials and/or crude products, to a pre-oxidation by treating with oxygen (for example, with air) at temperatures below the ignition temperature thereof.

It has surprisingly now been found that all these demands can be met if a mash of carbon-containing crude materials and phosphoric acid are subjected before activation to a rapid pre-oxidation and a rapid dehydration.

The first heat treatment or preoxidation and the carbonization can be carried out under conditions and in devices as taught by West German Accepted Specification 2,614,391 for the manufacture of carbon filaments.

After the preoxidation at three different temperatures, the test pieces were exposed to alternating thermal loading in the fluidized bed installation.

The total loading time during the alternating loading in the fluidized bed was therefore small in comparison with the duration of the preoxidation.

However, it must be noted that, during the operation of an actual machine (gas turbine etc.), the holding times are to be measured in hours or even in days, and that usually no preoxidation takes place there.

The pre-oxidation of the stainless steel or nickel alloy surface with hydrogen peroxide takes place in such a way that the coating can take place below 100° C. in an open or closed vessel, and also at temperatures above 100° C. in a closed vessel.

The reaction was carried out analogously to Example 1, but with the difference that instead of the copper(I) chloride, copper methoxychloride was used as catalyst, which had been prepared in the autoclave by preoxidation of the CuCl used (1.62 mol/l of MeOH) with oxygen (1.1 mol) at 120° C. and 20 bar of nitrogen admission pressure.

It has been found that carbon membranes with relatively large pores cannot be made by a process such as indicated in this publication, namely preoxidation and carbonization of a suitable starting material.

From the literature on the manufacture of nonporous carbon filaments and fibers, it is known that this first heat treatment, often also referred to as preoxidation, is necessary in order to be able to carry out the subsequent carbonization with sufficient dimensional stability.