Low-Cost High-Purity Vacuum Pumps and Systems

A furnace system for powder metallurgy with reduced contamination, comprising:

• a vacuum processing chamber configured to perform a debinding cycle at a debinding temperature sufficient to debind at least one part such that debinding by-products are off-gassed from the least one part, wherein the debinding cycle can be followed by a sintering cycle at a sintering temperature that is higher than the debinding temperature, the vacuum processing chamber having a pumping tube having an inlet end that is sealed to the vacuum processing chamber and an outlet end that is separated from the vacuum processing chamber by the pumping tube;
• a heating system including at least one heater configured to heat the pumping tube at least during the debinding cycle to at least a temperature sufficient to reduce condensation of contaminants within the pumping tube, including the debinding by-products outgassed from the vacuum processing chamber during the debinding cycle, to a predetermined threshold;
• a pumping system sealed to the outlet end of the pumping tube and configured to produce a vacuum in the vacuum processing chamber;
• and
• a process gas source configured to inject a sweep gas into the vacuum processing chamber at least during the sintering cycle such that the pumping tube provides an amount of Peclet sealing during sintering.

A furnace system for metal powder metallurgy with reduced contamination, comprising:

• a vacuum processing chamber configured to perform a debinding cycle at a debinding temperature sufficient to debind at least one part such that debinding by-products are off-gassed from the least one part, wherein the debinding cycle can be followed a sintering cycle at a sintering temperature that is higher than the debinding temperature, the vacuum processing chamber having a pumping tube having an inlet end that is sealed to the vacuum processing chamber and an outlet end that is separated from the vacuum processing chamber by the pumping tube;
• a first valve and a second valve each of which is sealed to the outlet of the pumping tube;
• a heating system including at least one heater configured to heat the pumping tube and the first valve and the second valve at least during the debinding cycle to at least a temperature sufficient to reduce condensation of contaminants within the pumping tube and within the first valve and the second valve, including the debinding by-products outgassed from the vacuum processing chamber during the debinding cycle, to a predetermined threshold;
• a first vacuum pump system, connected to the first valve, for pumping on the vacuum processing chamber during debinding through the pumping tube by way of the first valve,
• a second vacuum pump system, connected to the second valve, for pumping on the vacuum processing chamber during sintering through the pumping tube by way of the second valve, the second vacuum pumping system including a second mechanical vacuum pump mechanism within a hermetic pump housing configured to hermetically isolate the second mechanical vacuum pump mechanism from ambient air outside the hermetic pump housing, the second vacuum pump system further having a second pump inlet connected to the second valve and a second pump outlet;
• wherein the second pump outlet is hermetically sealed to an inlet of a Peclet seal tube;
• and
• at least one of:
• (1) a sweep gas source configured to inject a sweep gas into at least one of (i) the hermetic pump housing and (ii) the inlet of the Peclet seal tube;
• and (2) a process gas source configured to inject a process gas into the vacuum processing chamber;
• such that at least one of the sweep gas and a process gas flow through the Peclet seal tube from the inlet of the Peclet seal tube towards an outlet of the Peclet seal tube to substantially isolate against the backflow of the ambient air through the Peclet seal tube;
• and
• a controller configured to, during at least a portion of the debinding process, cause the first valve to be in an open position and the second valve to be in a closed position and operate the first mechanical vacuum pump to produce a vacuum in the vacuum processing chamber, and, during at least a portion of the sintering process, cause the first valve to be in a closed position and the second valve to be in an open position and operate the second mechanical vacuum to produce a vacuum in the vacuum processing chamber.

A method of operating a pumping system to reduce contamination, comprising:

• operating a mechanical vacuum pump to produce a vacuum in a vacuum processing chamber, wherein the mechanical vacuum pump is contained within a vacuum pump housing hermetically sealing the mechanical vacuum pump from an ambient air;
• wherein a pumping tube hermetically connects the vacuum processing chamber to a pump inlet of the vacuum pump housing;
• wherein a pump outlet hermetically connects the vacuum pump housing to an inlet of a Peclet seal tube;
• and
• operating a sweep gas source to inject a sweep gas into at least one of the hermetically sealed vacuum pump housing and the inlet of the Peclet seal tube, whereby the sweep gas isolates pump outlet, pump inlet and vacuum processing chamber against the backflow of the ambient air through the Peclet seal tube.