# US 4,395,299 A · Bonded bulk graphite and process for bonding

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- Number: US 4,395,299 A
- Document ID: US4395299A
- Status: Granted
- Kind: A
- Application number: 06/295,167
- Filed: 1981-08-21
- Granted: 1983-07-26
- Earliest claimed: 1981-08-21
- Assignees: The United States of America as represented by the Secretary of the Army
- Inventors: Dennis M. Riggs; Edward L. Harvey
- Web page: https://patentgrep.com/patent/US4395299A

## CPC

- C09J 5/06: involving heating of the applied adhesive
- C09J 195/00: Adhesives based on bituminous materials, e.g. asphalt, tar, pitch
- Y10T 428/30: Self-sustaining carbon mass or layer with impregnant or other layer
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Bulk pieces of graphite bonded with a graphitizable binder comprising a lid crystalline component of pitch, which softens at about 240.degree. C. and becomes very fluid at about 300.degree. C. to about 500.degree. C. The bonded graphite pieces appear as a monolithic material even under 1000.times. magnification. The bonding is effected under vacuum or in an inert atmosphere at temperatures of from about 700.degree. C. to about 3000.degree. C., usually about 1000.degree. C. to about 1500.degree. C., under pressure of from about 20 psi to about 1000 psi applied in a direction normal to the bonding surface.

## Claims

### Claim 1

A process for bonding graphite pieces together wherein a graphitizable binder consisting essentially of a liquid crystalline component of pitch obtained by extracting an isotropic pitch with a hydrocarbon solvent to yield a solvent insoluble fraction which softens at about 240.degree. C. and becomes very fluid at about 300.degree. C. to about 500.degree. C. is spread uniformly over at least one of the two graphite surfaces to be bonded together, the pieces are then joined and held in intimate contact and the entire assemblage is heated under vacuum or in an inert atmosphere to a temperature in the range of from about 700.degree. C. to about 3000.degree. C. under a pressure of from about 20 psi to about 1000 psi applied in a direction normal to the bond interface until bonding is effected.

### Claim 2 (depends on 1)

A process according to claim 1 wherein the heating process is in two stages, the first stage being gradually heating the article to a temperature of about 550.degree. C. and maintaining said temperature for a short time period followed by a second heating to a temperature in the range of from about 700.degree. C. to about 3000.degree. C.

### Claim 3 (depends on 2)

A process according to claim 2 wherein the assembly is heated at a temperature of from about 1000.degree. C. to about 1500.degree. C. under a pressure of about 200 psi until bonding is effected.

### Claim 4 (depends on 3)

A process according to claim 3 wherein the process is carried out in a vacuum.

### Claim 5 (depends on 4)

A process according to claim 4 wherein the thickness of the binder is of the order of 1/16 inch and the assembly is wrapped prior to heating.