GB/T 5158.4-2011Metallic powders -- Determination of oxygen content by reduction methods -- Part 4: Total oxygen by reduction-extraction (English PDF)

Foreword

GB/T 5158 "Metallic powders - Determination of oxygen content by reduction

methods" is divided into four parts:

- Part 1: General guidelines;

- Part 2: Loss of mass on hydrogen reduction (hydrogen loss);

- Part 3: Hydrogen-reducible oxygen;

- Part 4: Total oxygen by reduction-extraction.

This Part is Part 4 of GB/T 5158.

This Part is identical to ISO 4491-4:1989 "Metallic powders - Determination of oxygen

content by reduction methods - Part 4: Total oxygen by reduction-extraction".

For ease of use, the following editorial modifications have been made to this Part:

a) Change the word "this International Standard" to "this Part";

b) Use the decimal separator "." instead of the comma "," as the decimal separator;

c) Delete the foreword of the international standard.

This Part replaces GB/T 5158.4-2001 "Determination of the total oxygen content of the

metal powder reduction-extraction".

Compared with GB/T 5158.4-2001, the main changes in this Part are as follows:

- Delete the ISO foreword;

- Add normative references;

- Revise the parts of the previous standard that differ from ISO 4491-4:1989 TO be

consistent.

Annex A of this Part is an informative annex.

This Part was proposed by China Nonferrous Metals Industry Association.

This Part shall be under the jurisdiction of National Nonferrous Metals Standardization

Technical Committee.

This Part was drafted by Central South University Powder Metallurgy Research

Institute, Shandong Lanyue Technology Co., Ltd., and China Nonferrous Metals

Metallic powders - Determination of oxygen content by

reduction methods - Part 4: Total oxygen by reduction-

extraction

1 Scope

This Part of GB/T 5158 specifies a method for the determination of the total oxygen

content of metallic powders in concentrations up to 2 % (mass fraction) by reduction-

extraction at high temperature.

By agreement, this method is also applicable to the determination of the total oxygen

content of sintered metal materials.

This Part is applicable to all powders of metals, alloys, carbides (hard alloys) and

mixtures thereof which are non-volatile under the test conditions. The sample may be

in powder or compact form.

The analysis is carried out on the powder as supplied, but the method is not applicable

if the powder contains a lubricant or binder. If such substances are present, the method

may be used only if they can first be completely removed by a method not affecting the

oxygen content of the powder.

This Part shall be used in conjunction with GB/T 5158.1.

2 Normative references

The following documents are indispensable for the application of this document. For

the dated references, only the editions with the dates indicated are applicable to this

document. For the undated references, the latest edition (including all the amendments)

are applicable to this document.

GB/T 5158.1 Metallic powders - Determination of oxygen content by reduction

methods - Part 1: General guidelines (ISO 4491-4:1989, IDT)

3 Principle

A test portion of the sample is heated in a graphite crucible at high temperature, either

under vacuum or in a flow of an inert carrier gas. Oxygen in the sample is converted to

oxides of carbon. These are extracted and transformed completely to either carbon

A metal foil capsule may be used solely to facilitate the introduction of the sample into

the apparatus. In this case, the weight of the capsule shall be kept to a minimum.

Alternatively, the metal of the capsule can constitute the metal bath needed for

convenient extraction; in this case, the mass of the capsule is chosen to give the bath

test-portion mass ratio recommended for the particular analysis.

When the graphite crucible is used with a metal bath for several consecutive analyses,

it is necessary to degas the bath prior to the beginning of each extraction operation.

The bath/test-portion mass ratio is maintained larger than the recommended minimum

value. if necessary, by the periodic introduction of fragments of metal followed by

degassing of the bath.

The mass of the test portion shall be selected depending on the sensitivity of the

apparatus used and the expected oxygen content. Frequently, a mass between 0.1 g and

1 g is chosen.

6 Procedure