Method of making whisker reinforced high fracture toughness ceramic threaded fasteners

Patent metadata

Field	Value
Publication number	US-11268560-B2
Application number	US-201815910381-A
Country	US
Kind code	B2
Filing date	Mar 2, 2018
Priority date	Oct 21, 2015
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

A high temperature fastener including a bolt and a nut, where the bolt and the nut are constructed of an aluminum oxide ceramic material reinforced with silicon-carbide crystal whiskers or silicon nitride.

First claim

What is claimed:

1. A method of making a fastener comprising:
creating a mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers;
hot pressing the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at a high temperature and a high pressure creating a solid blank of hard ceramic material;
forming a screw threaded surface on the solid blank of hard ceramic material;
inserting a pre-form with external screw threads inside the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers prior to hot pressing the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at the high temperature and the high pressure creating the solid blank of hard ceramic material; and,
forming the screw threaded surface on the solid blank of hard ceramic material by cleaning the pre-form out of the solid blank of hard ceramic material leaving internal screw threads in the solid blank of hard ceramic material.

2. The method of claim 1 , further comprising:
creating the mixture of aluminum oxide ceramic material powder and silicon-carbide crystal whiskers with a percentage of silicon-carbide crystal whiskers in the mixture being in a range of 18% to 30% of the mixture.

3. The method of claim 1 , further comprising:
creating the solid blank of hard ceramic material with a head and a shaft.

4. The method of claim 3 , further comprising:
machining a tool interface surface on the head of the solid blank of hard ceramic material.

5. The method of claim 3 , further comprising:
machining a screw threaded exterior surface on the shaft of the solid blank of hard ceramic material.

6. The method of claim 5 , further comprising:
machining the screw threaded exterior surface with shallow valleys reducing a potential for crack initiation and reducing notch sensitivity.

7. A method of making a fastener comprising:
creating a mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers;
hot pressing the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at a high temperature and a high pressure creating a solid blank of hard ceramic material;
forming a screw threaded surface on the solid blank of hard ceramic material;
inserting a pre-form inside the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers prior to hot pressing the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at the high temperature and the high pressure creating the solid blank of hard ceramic material; and,
forming a cooling channel through the solid blank of hard ceramic material by cleaning the pre-form out of the solid blank of hard ceramic material leaving the cooling channel in the solid blank of hard ceramic material.

8. The method of claim 7 , further comprising:
creating the solid blank of hard ceramic material with a head and a shaft.

9. The method of claim 8 , further comprising:
machining a tool interface surface on the head of the solid blank of hard ceramic material.

10. The method of claim 8 , further comprising:
machining a screw threaded exterior surface on the shaft of the solid blank of hard ceramic material.

11. The method of claim 10 , further comprising:
machining the screw threaded exterior surface with shallow valleys reducing a potential for crack initiation and reducing notch sensitivity.

12. A method of making a fastener comprising:
creating a mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers;
hot pressing the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at a high temperature and a high pressure creating a solid blank of hard ceramic material;
forming a screw threaded surface on the solid blank of hard ceramic material;
inserting a pre-form inside the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers prior to hot pressing the mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at the high temperature and the high pressure creating the solid blank of hard ceramic material; and,
forming an internal tool interface surface in the solid blank of hard ceramic material by cleaning the pre-form out of the solid blank of hard ceramic material leaving the internal tool interface surface in the solid blank of hard ceramic material.

13. The method of claim 12 , further comprising:
creating the solid blank of hard ceramic material with a head and a shaft.

14. The method of claim 13 , further comprising:
machining a tool interface surface on the head of the solid blank of hard ceramic material.

15. The method of claim 13 , further comprising:
machining a screw threaded exterior surface on the shaft of the solid blank of hard ceramic material.

16. The method of claim 15 , further comprising:
machining the screw threaded exterior surface with shallow valleys reducing a potential for crack initiation and reducing notch sensitivity.

17. A method of making a fastener comprising:
creating a first mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers;
hot pressing the first mixture of aluminum oxide ceramic material powder and silico-carbide whiskers at a high temperature and a high pressure creating a solid first blank of hard ceramic material;
machining a screw threaded exterior surface on the solid first blank of hard ceramic material;
creating a second mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers;
inserting a pre-form with external screw threads into the second mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers;
hot pressing the second mixture of aluminum oxide ceramic material powder and silicon-carbide whiskers at the high temperature and the high pressure creating a solid second blank of hard ceramic material; and,
forming an internal screw threaded surface in the solid second blank of hard ceramic material by cleaning the pre-form out of the solid second blank of hard ceramic material leaving internal screw threads in the solid second blank of hard ceramic material.

18. The method of claim 17 , further comprising:
machining a tool interface surface on the solid second blank of hard ceramic material.

19. The method of claim 17 , further comprising:
machining the screw threaded exterior surface on the solid first blank of hard ceramic material with shallow valleys reducing a potential for crack initiation and reducing notch sensitivity.

20. The method of claim 17 , further comprising:
creating the first mixture of aluminum oxide ceramic material powder and silicon-carbide crystal whiskers with a percentage of silicon-carbide crystal whiskers in the first mixture being in a range of 18% to 30% of the mixture.

Assignees

• Boeing Co

Inventors

• Dichiara Robert A

Classifications

• C04B35/584

  based on silicon nitride · CPC title

• C04B35/117

  Composites · CPC title

• C04B35/645

  Pressure sintering · CPC title

• C04B35/593

  obtained by pressure sintering · CPC title

• B28B7/0064

  Moulds characterised by special surfaces for producing a desired surface of a moulded article, e.g. profiled or polished moulding surfaces (B28B7/36 takes precedence; producing decorative effects B44C; designs of stone surfaces B44F) · CPC title