Making articles of aluminum nitride

Claim 1

A METHOD OF MAKING AN ARTICLE OF ALUMINUM NITRIDE WHICH COMPRISES THE STEPS OF PRESSING A POWDER INTO THE FORM OF A COHERENT BODY OF THE POWDER, SAID POWDER CONSISTING OF A MIXTURE OF ALUMINUM POWDER AND UP TO 50% OF ALUMINUM NITRIDE POWDER, AND SAID BODY HAVING SUBSTANTIALLY THE SHAPE AND DIMENSIONS OF THE ARTICLE TO BE MADE, GRADUALLY HEATING SAID BODY INA NITROGENOUS ATOMSPHERE UNTIL A TEMPERATURE OF 660*C. IS PASSED, SAID HEATING BEING EFFECTED IN THE PRESENCE OF AN INORGANIC METAL FLUORIDE SELECTED FROM THE GROUP CONSISTING OF THE FLUORIDES OF ALUMINUM, BARIUM, CALCIUM, LITHIUM, MAGNESIUM, POTASSIUM AND SODIUM, WHICH FLUROIDES ARE CATALYSTS FOR THE CONVERSION OF ALUMINUM TO ALUMINUM NITRIDE, SAID HEATING FURTHER BEING SCHEDULED IN STAGES AT GRADUALLY INCREASING TEMPERATURES AND OF DURATIONS ENSURING CONVERSION OF ALUMINUM TO ALUMINUM NITRIDE AND STABILISATION OF SAID SHAPE AND DIMENSIONS BEFORE SAID TEMPERATURE OF 660*C. IS REACHED, AND THEN CONTINUING HEATING OF SAID BODY AT ABOVE SAID TEMPERATURE OF 660*C. UNTIL SAID BODY CONSISTS SUBSTANTIALLY ENTIRELY OF ALUMINUM NITRIDE.