GOST 30642-99

• gost-30642-99.pdf (204.88 KiB)
  ГОСТ 30642-99

GOST 30642−99 (ISO 7625−83) Materials powder (sintered metal), excluding hardmetals. Sample preparation for chemical analysis for determination of carbon

GOST 30642−99
(ISO 7625−83)

Group B59

INTERSTATE STANDARD

MATERIALS POWDER (SINTERED METAL),
EXCLUDING HARD ALLOYS

Sample preparation for chemical analysis for determination of carbon

Sintered metal materials, excluding hardmetals.
Preparation of samples for chemical analysis for determination of carbon content

ISS 77.160
AXTU 1790

Date of introduction 2001−07−01

Preface

1 DEVELOPED by the Interstate technical Committee for standardization MTK 150, Institute for problems of materials science I. N. Frantsevich of NAS of Ukraine

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (minutes N 15 of 28 may 1999)

The adoption voted:

3 this standard contains the full authentic text of international standard ISO 7625−83 «sintered metal Materials, excluding hardmetals. Sample preparation for chemical analysis for determination of carbon» with additional requirements that reflect the needs of the economy, which in the text are highlighted in italics

4 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated December 19, 2000 N 384-St inter-state standard GOST 30642−99 (ISO 7625−83) introduced directly as a state standard of the Russian Federation from July 1, 2001

5 INTRODUCED FOR THE FIRST TIME

Introduction

Chemical analysis of sintered metal (powder according to GOST 17359) materials, excluding hard metals, is performed using available standard methods for compact metals (molten metals and their alloys).

As sintered materials very frequently contain carbon in different conditions, the correct determination of the mass fraction of free or total carbon requires the observance of certain precautions in the preparation of samples for analysis of their composition.

Samples prepared in accordance with the requirements of this standard are also suitable for chemical analysis for determination of other elements.

1 Scope

This standard specifies the methods of preparation of samples of material (products) in the form of chips or powder to determine the concentration of free or total carbon.

Fixed carbon is determined as the difference between total and free carbon. The standard provides for sample preparation for the determination of carbon by chemical method, i.e. burning them in oxygen with the subsequent determination of the resulting carbon dioxide.

Sample preparation for the determination of carbon by physical methods (metallography or spectroscopy) standard does not provide.

The standard covers products made of materials with a homogeneous distribution of carbon stored in the condition shown in table 1, and satisfies the conditions of determination given in table 2.


Table 1 — carbon As determined by chemical analysis

Table 2 — Sources of carbonaceous substances and the possibility of determination of carbon by chemical methods

The standard does not apply to products with non-uniform distribution of carbon throughout the volume (e.g. in products with a hardened surface layer).

The presence of carbonaceous substances in the pores or on the surface of the analyzed products (table 2) interferes with the determination of carbon.

2 Normative references

The present standard features references to the following standards:

GOST 17359−82 Powder metallurgy. Terms and definitions

GOST 18898−89 (ISO 2738−87) powder Products. Methods of determination of density, oil content and porosity

GOST 24903−81 Powder products. Method for determination of oil

3 the essence of the method

Sample preparation for analysis is carried out by removing from the sample material impregnated in the pores or surface of the carbon with subsequent mechanical crushing of samples that exclude (needs to follow) losses contained in the material free of carbon.

4 Procedure sample preparation

4.1 a Sample selected based on regulatory documents for a specific material (product), and prepared in accordance with the requirements of 4.2 and 4.3.

4.2 Removal of carbon substances that prevent analysis

Carbonaceous matter (table 2), distorting the results of determination of carbon, should be removed from the sample or item to the analysis in the following way.

4.2.1 Organic substance impregnated in the pores or on the surface of the sample or product (table 2, items 1, 2), should be removed by degreasing Soxhlet at 18898 GOST or GOST 24903 using an appropriate solvent.

Note — If the liquid for impregnation contains tiny carbon particles, for example colloidal graphite, degreasing Soxhlet can be removed only part of these particles. In this case, the determination of free and total carbon will be invalid, despite the fact that the calculation of fixed carbon in this case is possible under condition of determination of the content of free and total carbon for the same product or products after degreasing.

4.2.2 Superficial deposits of carbon on the sample or product (table 2, item 3) remove mechanical treatment.

4.3 Final sample preparation

The analyzed sample should consist of small pieces or be in the form of powder with particle size that conforms to the applicable method of analysis and must be obtained in one of the following ways:

— grinding in a mortar made of a material that does not alter the composition of a sample;

— drilling, milling or grinding.

The specified mechanical processing must be performed without cooling the sample fluid. Measures must be taken against overheating, oxidation and contamination particles. If drilling is used, the product must be drilled through, and the distribution of drilled holes should be uniform across the surface of the product. The product is thick holes drilled from two sides to the middle.

If the pieces after the grinding or machining may contain small particles, such as free graphite, it is necessary to take precautions to avoid losing them during processing.

Note — In the case of all bundles received in the form of small pieces or powder sample should be after careful averaging is divided into the appropriate (necessary) number of analyzed batches. The carbon content is calculated as the average of the results of the analysis of each sample.


Prepared a number of samples should be representative of the product or products. To protect against contamination of samples for analysis should be stored in a desiccator with a tightly fitting lid without lubricant.

Requirements for long-term storage of samples should be specified in regulatory documents for specific product.

On each Packed sample should be specified:

— product name and grade of the material;

— the batch number;

— basic techniques of sample preparation with reference to this standard;

— date of preparation of the sample.