Refractory powder comprising coated mullite grains
AssigneeSaint-Gobain Centre De Recherches Et D'Etudes Europeen
InventorsThibault Champion, Christian His
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Abstract
A powder is disclosed having a coarse fraction representing more than 60% and less than 85% of the powder, as a weight percentage on the basis of the oxides, and that is constituted of particles having a size greater than or equal to 50 μm, referred to as “coarse particles”, the powder comprising at least 5% of coated grains having a size greater than or equal to 50 μm, as a weight percentage on the basis of the oxides of the powder, and a fine fraction, forming the balance to 100% as a weight percentage on the basis of the oxides, constituted of particles having a size of less than 50 μm, referred to as “matrix particles”. The powder can be applied in combustion chambers in which the temperature may reach 1400° C.
Claims25
A powder comprising:
- a coarse fraction representing more than 60% and less than 85% of the powder, as percentage by weight based on the oxides, and consisting of particles exhibiting a size of greater than or equal to 50 μm, referred to as “coarse particles”, the powder comprising at least 5% of coated grains exhibiting a size of greater than or equal to 50 μm, as percentage by weight based on the oxides of the powder, and
- a fine fraction, forming the remainder to 100% as percentage by weight based on the oxides, consisting of particles exhibiting a size of less than 50 μm, referred to as “matrix particles”,
- said coated grains each comprising:
- a base grain comprising more than 30% by weight of mullite;
- a coating extending over more than 50% of the surface of said base grain and consisting, for more than 90% of its weight, of a coating material chosen from:
- alumina;
- CaSiO3;
- lanthanide, Ta, Ti, Sc, Y, Mg , Mo aluminates and their mixtures;
- lanthanide, Sc, Y, Zr , Hf silicates and their mixtures;
- oxides of one or more elements chosen from Ti, Sc, Y, Yb, Mg, Ce, Mo, Zr and Hf;
- lanthanide and/or Y and/or Sc phosphates;
- and their mixtures,
- the powder comprising more than 20% of particles exhibiting a size greater than 150 μm, as percentage by weight based on the oxides of the powder,
- the powder exhibiting a content of alumina of greater than 70%, as percentage by weight based on the oxides.
A sintered product manufactured according to a process comprising the following successive stages:
- A) preparation of a starting charge by addition of water to a powder comprising:
- a coarse fraction representing more than 60% and less than 85% of the powder, as percentage by weight based on the oxides, and consisting of particles exhibiting a size of greater than or equal to 50 μm, referred to as “coarse particles”, the powder comprising at least 5% of coated grains exhibiting a size of greater than or equal to 50 μm, as percentage by weight based on the oxides of the powder, and
- a fine fraction, forming the remainder to 100% as percentage by weight based on the oxides, consisting of particles exhibiting a size of less than 50 μm, referred to as “matrix particles”,
- said coated grains each comprising:
- a base grain comprising more than 30% by weight of mullite;
- a coating extending over more than 50% of the surface of said base grain and consisting, for more than 90% of its weight, of a coating material chosen from:
- alumina;
- CaSiO3;
- lanthanide, Ta, Ti, Sc, Y, Mg , Mo aluminates and their mixtures;
- lanthanide, Sc, Y, Zr , Hf silicates and their mixtures;
- oxides of one or more elements chosen from Ti, Sc, Y, Yb, Mg, Ce, Mo, Zr and Hf;
- lanthanide and/or Y and/or Sc phosphates;
- and their mixtures,
- B) shaping said starting charge so as to form a preform;
- C) sintering said preform,
- the product exhibiting the appearance of a block or of a layer, said block or layer having a thickness greater than 3 mm.
Dependencies are inferred from the claim text.