with the formation of carbon further to the carbon monoxide atmosphere carbon is preferably present in the sintering oven during the final sintering step the carbon can be present as an element for example in the form of graphite or in a gaseous chemical compound for instance a hydrocarbon liable to decompose partially or totally with formation of carbon a preferred device for placing into operation the process of the present invention comprises means of feeding into the sintering over free or chemicaly bound carbon such means can be provided by injectors fed with pulverulent graphite of compounds as hereinabove defined in yet another preferred device for placing into operation the process of the present invention the components of the oven brought to the highest temperature such as a susceptor for heating by induction or a resistor for heating by electrical resistance the container and its support are made of carbon such as graphite they are not therefore damaged by the carbon monoxide atmosphere a better understanding of the present invention will be gained from the following examples which are merely intended to be illustrative and not limitative of the present invention from a mixture of u03b3 alumina and an addition of 0 06 of mgo a pressing grain was produced by adding to the aforesaid mixture 8 by weight of said mixture of a glycol stearate binder the grain was pressed in the form of wafers exhibiting a thickness of 1 5 mm with a crude density of 2 2 the pressed articles were purified by pre sintering in an oxidized atmosphere of air at 1350 u00b0 c the articles.