Die and piston of an sps apparatus, sps apparatus comprising same, and method of sintering, densification or assembly in an oxidising atmosphere using said apparatus

Patent metadata

Field	Value
Publication number	US-2023133590-A1
Application number	US-202218146567-A
Country	US
Kind code	A1
Filing date	Dec 27, 2022
Priority date	Nov 4, 2015
Publication date	May 4, 2023
Grant date	—

Abstract

A die or piston of a spark plasma sintering apparatus, wherein the die or piston is made from graphite and the outer surfaces of the die or piston are coated with a silicon carbide layer with a thickness of 1 to 10 micrometres, the silicon carbide layer being further optionally coated with one or more other layer(s) made from a carbide other than silicon carbide chosen from hafnium carbide, tantalum carbide and titanium carbide, the other layer(s) each having a thickness of 1 to 10 micrometres. A spark plasma sintering (SPS) apparatus comprising the die and two of the pistons, defining a sintering, densification or assembly chamber capable of receiving a powder to be sintered, a part to be densified, or parts to be assembled. A method of sintering a powder, densifying a part, or assembling two parts by means of a method of spark plasma sintering (SPS) in an oxidising atmosphere, using the spark plasma sintering (SPS) apparatus.

First claim

1 . A spark plasma sintering (SPS) method for sintering a powder, densifying a part, or assembling two parts, said method comprising the steps of:
placing said powder, part or two parts into an SPS apparatus, said SPS apparatus comprising a die and two pistons that define a sintering, densification or assembly chamber capable of receiving a powder to be sintered, a part to be densified, or parts to be assembled, wherein each of said pistons is made of graphite and the outer surfaces of each of said pistons are coated with a homogenous layer made of silicon carbide having a thickness of 1 to 10 μm; and applying a pulsed electric current to the powder, part or two parts, wherein the pulsed electric current is sufficient to raise the temperature of the powder, of the part, or of the parts to a temperature to between 700° C. and 1450° C.; and wherein the method takes place in an oxidizing atmosphere.

2 . The method according to claim 1 , wherein the oxidizing atmosphere is an atmosphere of gas containing oxygen selected from pure oxygen, ambient air, and air enriched with oxygen.

3 . The method according to claim 2 , wherein the oxidizing atmosphere is ambient air.

4 . The method according to claim 1 , wherein after sintering of the powder, densification of the part, or assembly of the two parts by the SPS method, the sintered powder, the densified part, or the assembly of the two parts is cooled to ambient temperature, and the cooled sintered powder, the cooled densified part, or the cooled assembly of the two parts is recovered.

5 . The method according to claim 1 , wherein the powder to be sintered, the part to be densified, or the parts to be assembled are made of a material chosen from metals, alloys of metals, oxides of metals or of metalloids, including the mixed oxides of metals or of metalloids, carbides of metals or of metalloids, nitrides of metals or of metalloids, and mixtures thereof.

6 . The method according to claim 5 , wherein the sintering of a powder of an oxide of a metal or of a metalloid or of a mixture of powders of oxides of a metal or of a metalloid is carried out.

7 . The method according to claim 6 , wherein the oxide(s) of a metal or of a metalloid is(are) chosen from TiO 2 , Al 2 O 3 , BaTiO 3 , and perovskites.

8 . The method according to claim 7 , wherein the oxide(s) of a metal or metalloid has the formula Ca 0.9 Yb 0.1 MnO 3-x .

9 . The method according to claim 5 , wherein the material is one or more oxides of metals or of metalloids, and wherein during sintering, the reduction of the oxide is avoided.

10 . The method according to claim 1 , wherein the layer made of silicon carbide is further coated with one or more other layer(s) made of a carbide other than silicon carbide, chosen from hafnium carbide, tantalum carbide and titanium carbide, said other layer(s) each having a thickness of 1 to 10 μm, and wherein the layer made of silicon carbide is the layer in direct contact with the outer surface of the graphite.

11 . The method according to claim 1 , wherein during operation of the SPS apparatus, the die and pistons conduct a pulsed current from 200 to 6000 A.

12 . The method according to claim 1 , wherein during operation of the SPS apparatus, the die and pistons conduct a voltage of 1 to 8 volts.

13 . The method according to claim 1 , wherein the temperature is maintained for 0 to 10 minutes.

14 . The method according to claim 13 , wherein the temperature is maintained for between 3 and 7 minutes.

15 . The method according to claim 1 , wherein the silicon carbide layer is applied using chemical vapor deposition (CVD).

16 . The method according to claim 1 , wherein the chamber is not placed under vacuum.

17 . The method according to claim 1 , wherein, upon visual inspection at the end of the method, said pistons showed no visible signs of damage following operation in said oxidizing atmosphere.

18 . The method according to claim 1 , wherein the method is complete in about 1 hour or less.

19 . The method according to claim 1 , wherein the SPS apparatus further comprises one or more plates, one or more spacers and one or more discs, any of which are made of graphite that is not coated with silicon carbide.

20 . A spark plasma sintering (SPS) method for sintering a powder, densifying a part, or assembling two parts, said method comprising the steps of:
placing said powder, part or two parts into an SPS apparatus, said SPS apparatus comprising a die and two pistons that define a sintering, densification or assembly chamber capable of receiving a powder to be sintered, a part to be densified, or parts to be assembled, wherein said die is made of graphite and the outer surfaces of said die are coated with a homogenous layer made of silicon carbide having a thickness of 1 to 10 μm; and applying a pulsed electric current to the powder, part or two parts, wherein the pulsed electric current is sufficient to raise the temperature of the powder, of the part, or of the parts to a temperature to between 700° C. and 1450° C.; and wherein the method takes place in an oxidizing atmosphere.

Assignees

• Cmmissariat A Lenergie Atomique Et Aux Energies Al Ternatives
• Centre Nat Rech Scient

Inventors

• Allemand Alexandre
• Largeteau Alain
• U-Chan Chung Seu
• Le Petitcorps Yann
• Roger Jérôme

Classifications

• C04B2235/6585

  at an oxygen percentage above that of air · CPC title

• C04B2235/3208

  Calcium oxide or oxide-forming salts thereof, e.g. lime · CPC title

• B22F2003/1051

  by electric discharge · CPC title

• C23C16/32

  Carbides · CPC title

• C04B2235/3224

  Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide · CPC title