Hybrid Sandwich Ceramic Matrix Composite

Patent metadata

Field	Value
Publication number	US-2016264476-A1
Application number	US-201514593682-A
Country	US
Kind code	A1
Filing date	Jan 9, 2015
Priority date	Jan 9, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

A hybrid sandwich ceramic matrix composite (CMC) may comprise a first facesheet, a second facesheet, and a core between and bonded to both of the first facesheet and the second facesheet. The first facesheet and the second facesheet may each include filaments in a ceramic matrix. The hybrid sandwich CMC may be configured for exposure to a thermal gradient in which the first facesheet is exposed to a higher temperature environment than the second facesheet. The first facesheet and the second facesheet may have at least closely matching coefficients of thermal expansion, and the first facesheet may have a higher compressive strength than the second facesheet.

First claim

1 . A diatomaceous earth product comprising:
natural diatomaceous earth; potassium silicate; and no more than about 4 wt % of crystalline silica after the natural diatomaceous earth and potassium silicate are combined to form a mixture and the mixture is calcined at a temperature between about 927° C. and about 1149° C., wherein the diatomaceous earth product has a permeability in the range of about 0.3 darcy to greater than about 20 darcy.

2 . The diatomaceous earth product of claim 1 wherein the mixture is free of organic burnout material.

3 . (canceled)

4 . The diatomaceous earth product of claim 1 , wherein the permeability ranges from about 0.8 darcy to about 20 darcy.

5 . The diatomaceous earth product of claim 1 , wherein the potassium silicate is present in an amount ranging from about 1 wt % to about 10 wt %.

6 . The diatomaceous earth product of claim 1 , wherein the permeability ranges from about 1 darcy to about 20 darcy.

7 . The diatomaceous earth product of claim 1 , wherein the permeability ranges from about 1.2 darcy to about 16 darcy.

8 . The diatomaceous earth product of claim 1 , wherein the crystalline silica is no more than about 2 wt %.

9 . The diatomaceous earth product of claim 1 , further comprising:
a setting agent comprising calcium lignosulfonate and magnesium hydroxide.

10 . The diatomaceous earth product of claim 5 , wherein the amount of potassium silicate ranges from about 2 wt % to about 5 wt %.

11 . A process for making a low crystalline silica content diatomaceous earth product, comprising:
providing natural diatomaceous earth; treating the natural diatomaceous earth with no more than about 5 wt % potassium silicate to make a mixture; and subjecting the mixture to at least one calcination step, wherein the at least one calcination step is conducted between about 927° C. and about 1149° C., wherein the diatomaceous earth product has a permeability in the range of about 0.3 darcy to greater than about 20 darcy, and wherein the diatomaceous earth product has a crystalline silica content of no more than about 4 wt %.

12 . (canceled)

13 . The process of claim 11 , wherein the at least one calcination step is conducted between about 982° C. and about 1093° C.

14 . The process of claim 11 , wherein the mixture contains no organic burnout material.

15 . The process of claim 14 , wherein the potassium silicate ranges from about 2 wt % to about 5 wt %.

16 . The process of claim 11 , wherein the permeability ranges from about 1 darcy to about 20 darcy.

17 . The process of claim 11 , further comprising a step of:
treating the mixture with a setting agent before the at least one calcination step, wherein the setting agent comprises calcium lignosulfonate and magnesium hydroxide

18 . A diatomaceous earth filter aid comprising:
at least about 95 wt % natural diatomaceous earth; and about 5 wt % or less potassium silicate; wherein the natural diatomaceous earth and potassium silicate are combined to form a mixture and calcined at a temperature between about 927° C. and about 1149° C. for at least about 45 minutes to provide the diatomaceous earth filter aid having a crystalline silica content no more than about 4 wt % and a permeability in the range of about 0.3 darcy to greater than about 20 darcy.

19 . The diatomaceous earth filter aid of claim 18 , wherein the mixture contains no organic burnout material.

20 . The diatomaceous earth filter aid of claim 18 , wherein the permeability ranges from about 1 darcy to about 20 darcy.

Assignees

• Boeing Co

Inventors

• Keith William P

Classifications

• B32B18/00 Primary

  Layered products essentially comprising ceramics, e.g. refractory products · CPC title

• B64C1/00

  Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like · CPC title

• C04B2237/84

  Joining of a first substrate with a second substrate at least partially inside the first substrate, where the bonding area is at the inside of the first substrate, e.g. one tube inside another tube · CPC title

• C04B2235/9607

  Thermal properties, e.g. thermal expansion coefficient · CPC title

• B32B2605/18

  Aircraft · CPC title