50 u03bcm preferably less than 40 u03bcm preferably less than 20 u03bcm preferably less than 10 u03bcm or even less than 5 u03bcm this advantageously improves densification of the part during the sintering step it is also preferable for the starting charge to include more than 10 of chamotte the structure of chamotte particles advantageously improves compacting while the green part is being formed the chamotte may be obtained by sintering powders of cr 2 o 3 and or al 2 o 3 and or tio 2 and or zro 2 and then grinding the chamotte may in particular come from recycling a product of the invention the maximum particle size of the chamotte is preferably less than 150 u03bcm preferably less than 100 u03bcm preferably the chamotte powder presents a median size less than 50 u03bcm preferably less than 20 u03bcm the chamotte content is preferably less than 50 or even less than 30 in addition to the raw materials measured out so that the sintered product has the desired average chemical composition by weight the starting charge may also conventionally include usual binders e g an organic binder and or deflocculants in step b the mixture prepared in step a may be poured into a mold and then shaped so as to form.