# US 6,297,058 B1 · Process for determining impurities in refractory materials

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- Number: US 6,297,058 B1
- Document ID: US6297058B1
- Status: Granted
- Kind: B1
- Application number: 09/231,025
- Filed: 1999-01-14
- Granted: 2001-10-02
- Earliest claimed: 1999-01-14
- Assignees: Agere Systems Optoelectronics Guardian Corp.
- Inventors: William David Reents, Jr.
- Web page: https://patentgrep.com/patent/US6297058B1

## CPC

- G01N 33/004: {CO or CO2}
- G01N 33/005: {H2}
- G01N 33/38: Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
- Y10T 436/23: Carbon containing
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A small sample of a refractory material, e.g., about 0.1 g to about 10 g, is heated to at least 1000° C., generally under a pressure of less than about 10−5 Torr. Evolved hydrogen-containing gases and/or carbon-containing gases are monitored, e.g., by mass spectrometry, and, based on the amount of the evolved gases, the concentration of hydrogen and/or carbon in the sample is calculated. It is therefore possible to accurately determine the hydrogen and carbon concentration from a small sample of a material, by a process much less burdensome than conventional techniques.

## Claims

### Claim 1

A process for fabricating a refractory article, comprising the steps of:
(a) heating a silica sample to at least 1000° C.;
(b) monitoring at least one of evolved hydrogen-containing gases and evolved carbon-containing gases;
(c) cooling the sample and adding hydrogen to the cooled sample;
(d) subsequent to adding hydrogen, reheating the sample to at least 1000° C. and monitoring evolved carbon-containing gases;
(e) optionally repeating steps (c) and (d); and
(f) based on the amount of the evolved gases, calculating the concentration of at least one of hydrogen and carbon in the sample.

### Claim 2 (depends on 1)

The process of claim 1, wherein the sample has a weight of about 0.1 g to about 10 g.

### Claim 3 (depends on 1)

The process of claim 1, wherein the sample is heated to at least 1400° C. during at least one of the heating step and the reheating step.

### Claim 4 (depends on 1)

The process of claim 1, wherein the heating and reheating steps are performed at a pressure less than about 10−5 Torr, and wherein the monitoring is performed by mass spectrometry.

### Claim 5 (depends on 1)

The process of claim 1, wherein the evolved gases comprise H2, CO2, and H2CO.

### Claim 6 (depends on 1)

The process of claim 1, wherein the sample is supported and heated by a platinum coil, wire, ribbon, or grid.

### Claim 7 (depends on 1)

The process of claim 1, wherein a radial profile is obtained for at least one of carbon concentration and hydrogen concentration.

### Claim 8

A process for fabricating a refractory article, comprising the steps of:
heating a silica body to at least 1000° C.;
cooling the body and adding hydrogen to the cooled body; and
subsequent to adding hydrogen, reheating the body to at least 1000° C.,
wherein the added hydrogen promotes evolution of carbon-containing species from the body.