Sintering of metal and alloy powders by microwave/millimeter-wave heating
View Patent ↗A method of sintering by: placing a compacted metal powder inside a cylindrically-shaped susceptor and in an inert atmosphere or a vacuum, and applying microwave or millimeter-wave energy to the powder until the powder is sintered.
1. A method comprising:
placing a compacted metal powder inside a cylindrically-shaped susceptor and in an inert atmosphere or a vacuum; and
applying microwave or millimeter-wave energy to the powder until the powder is sintered;
wherein the susceptor coaxially surrounds the microwave or millimeter-wave energy.
2. The method of claim 1 , wherein the compacted metal powder comprises titanium.
3. The method of claim 1 , wherein the compacted metal powder comprises titanium and one or more other metals.
4. The method of claim 1 , wherein the compacted metal powder comprises an alloy of titanium and one or more other metals.
5. The method of claim 1 , wherein the compacted metal powder has a density of at least about 30% of the bulk density of the metal.
6. The method of claim 1 ;
wherein the compacted metal powder has a density of 30-90% of the bulk density of the metal; and
wherein the sintered powder has a porosity of 50% or less.
7. The method of claim 1 , wherein the microwave or millimeter-wave energy has a frequency of from 0.9 to 90 GHz.
8. The method of claim 1 , wherein applying the energy heats at least a portion of the powder to a temperature from about half the melting point of the metal powder to a temperature below the melting point of the powder.
9. The method of claim 1 , wherein applying the energy is performed for about 10 minutes to about 1 hour.
10. The method of claim 1 , wherein applying the energy is performed for more than 1 hour.
11. The method of claim 1 , wherein the energy passes through an open end of the cylindrical susceptor before contacting the powder.
12. The method of claim 11 , further comprising:
monitoring the temperature of the powder using a pyrometer.
13. The method of claim 1 , wherein the energy passes through a 3-stub tuner before entering a chamber containing the susceptor and powder.
14. The method of claim 1 , wherein an oxygen sensor is in a chamber containing the susceptor and powder.
15. The method of claim 14 , wherein the chamber comprises an atmospheric control port.