Method for carbon control of carbide preforms

A method for controlling the carbon content of dewaxed carbide preforms in a carbon containing furnace comprising the steps of:

• placing the preforms in the carbon containing furnace,
• heating the furnace to a predetermined temperature range in which the chemical reaction,
• C.sub.solid +SH.sub.2 .revreaction.CH.sub.4 reaches equilibrium in a first time period at a selected pressure and in which the chemical reaction
• XC+2H.sub.2 .revreaction.X+CH.sub.4
• where X is selected from the group of W, Ti, Ta, Hf and Mo, reaches equilibrium in a second time period at said selected pressure, said second time period being shorter in duration than said first time period or the resident time of the gaseous mixture is less than the second time period,
• introducing H.sub.2 into said furnace so that said H.sub.2 reacts with carbon in the furnace to form CH.sub.4 wherein the percentage of CH.sub.4 is between 10% and 90% necessary to form equilibrium of the reaction
• C.sub.solid +2H.sub.2 .revreaction.CH.sub.4
• at said selected pressue and said temperature range, and
• maintaining said furnace at said temperature range for a duration between said first and second time periods.