Abradable composition, a method of manufacturing an abradable composition and a gas turbine engine having an abradable seal

A method of manufacturing an abradable composition comprising the steps of:

• (a) forming a paste of aluminum phosphate including mixing aluminosilicate powder and water with alumina powder and phosphoric acid to form the paste in the amount of 54.3 wt % aluminosilicate powder, 23.3 wt % alumina powder and 22.4 wt % of 96% phosphoric acid and water,
• (b) adding hollow aluminosilicate spheres to the paste,
• (c) mixing the paste and hollow aluminosilicate spheres to form a ceramic slurry,
• (d) moulding the ceramic slurry of hollow aluminosilicate spheres and paste to a required shape,
• (e) heat treating the moulded ceramic slurry of hollow aluminosilicate spheres and paste to form an aluminum phosphate matrix containing hollow aluminosilicate spheres.

A method of manufacturing an abradable composition comprising the steps of:

• (a) forming a paste of aluminum phosphate including mixing aluminosilicate powder with mono aluminum phosphate solution to form the paste in the amount of 53.8 wt % aluminosilicate powder and 46.2 wt % mono aluminum phosphate solution,
• (b) adding hollow aluminosilicate spheres to the paste,
• (c) mixing the paste and hollow aluminosilicate spheres to form a ceramic slurry,
• (d) moulding the ceramic slurry of hollow aluminosilicate spheres and paste to a required shape,
• (e) heat treating the moulded ceramic slurry of hollow aluminosilicate spheres and paste to form an aluminum phosphate matrix containing hollow aluminosilicate spheres.

A method of manufacturing an abradable composition comprising the steps of:

• (a) forming a paste of aluminum phosphate,
• (b) adding hollow aluminosilicate spheres to the paste,
• (c) mixing the paste and hollow aluminosilicate spheres to form a ceramic slurry,
• (d) moulding the ceramic slurry of hollow aluminosilicate spheres and paste to a required shape,
• (e) heat treating the moulded ceramic slurry of hollow aluminosilicate spheres and paste for 10 hours at 60.degree. C., for 1 hour at 120.degree. C., for 1.5 hours at 350.degree. C., for 2 hours at 800.degree. C., for 2 hours at 1100.degree. C. and for 1 hour at 1200.degree. C. to form an aluminum phosphate matrix containing hollow aluminosilicate spheres.