| 摘要 |
The invention provides a powder comprising at least 95% by number of fused grains, with the following chemical composition, as a percentage by weight based on the oxides, for a total of 100%: 0<=BaO<=40.8%; 0<=SrO<=31.8%; 27.2%<=Al2O3<=31.3%; 32%<=SiO2<=36.9%; other species<=1%; the quantity of at least one of the oxides BaO and SrO being more than 0.3%, the size of said grains being such that D5>=5 mum and D95<=150 mum.
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