GOST 18318-94

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  ГОСТ 18318-94

GOST 18318−94 Powder metal. Determination of particle size by dry sieving

GOST 18318−94

Group B59

INTERSTATE STANDARD

POWDER METAL

Determination of particle size by dry sieving

Metallic powders. Determination of particle size by dry sieving

OKS 77.120*
AXTU 1790
____________________
* In the index «National standards», 2008
OKS 77.160. — Note the manufacturer’s database.

Date of introduction 1997−01−01

Preface

1 DEVELOPED by the Institute for problems of materials science im. I. N. Frantsevich of NAS of Ukraine, Technical Committee TC 150 «Powder metallurgy"

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

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol N 6 of October 21, 1994)

The adoption voted:

Annex a of this standard is a full authentic text of international standard ISO 4497−83 «Powder metal. Determination of particle size by dry sieving"

3 Decree of the Russian Federation Committee on standardization, Metrology and certification dated June 19, 1996 N 400 interstate standard GOST 18318−94 introduced directly as state standard of the Russian Federation from January 1, 1997

4 REPLACE GOST 18318−73

1 SCOPE

This standard specifies a method for determining the distribution of particle size (granulometric composition) of metal powders dry sieving them into fractions.

The method consists in sifting the sample of powder through a set of sieves, weighing the individual fractions and calculating percentages.

The standard does not apply to powders with plasticizers, particle shape, significantly different from the equiaxed (flake, needle-like, dendritic and lamellar), as well as powders, the particle size of which, or more of less than 45 microns.

Allowed measurement of particle size of powders by dry sieving ISO 4497, given in Appendix A.

Standard suitable for certification purposes.

2 NORMATIVE REFERENCES

The present standard features references to the following standards:

GOST 6613−86 Grids wire woven with square cells. Specifications

GOST 23148−78* Powder metal. Methods of sampling and sample preparation
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* On the territory of the Russian Federation GOST 23148−98, here and hereafter. — Note the manufacturer’s database.

GOST 24104−88* laboratory Scales General purpose and model. General specifications
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* On the territory of the Russian Federation GOST 24104−2001, here and hereafter. — Note the manufacturer’s database.

3 SAMPLING

3.1 a Sample for testing taken from the powder in the delivery state according to GOST 23148.

If the bulk density of the test powder is more than 1.5 g/cm, then the sample mass must be (100±1) g. For powders with a bulk density of 1.5 g/cmand less than the sample mass should be (50,0±0,5) g.

Allowed to dry the powder prior to the test, ensuring the safety of its particle size distribution. If the powder is oxidized, drying is carried out in vacuum or in an inert gas stream.

3.2 the Sample is weighed with an error not more than 0.05 g. the weighing Results are rounded to the first decimal place for samples with a mass of (100±1) g and to a multiple of five in the second decimal sign, for samples of weight (50,0±0,5) g.

3.3 Number of samples for testing must be specified in the normative documentation on the specific powder.

4 EQUIPMENT

Set (set) sieves with lid and pan. Sieves should be round with a shell diameter of 200 mm and a depth of from 25 to 50 mm.

The mesh sizes of sieves — according to GOST 6613.

The sizes of sieves should correspond to the preferred numbers in the series R 20/3. Allowed to replace them with one of the intermediate sizes R 40/3 series or master series R 20.

Shell and mesh of the sieves shall be made of non-magnetic materials.

The shell of the sieves and the tray should fit snugly to each other and close the lid.

The sizes of sieves during the sieving of the powder is selected so that significant parts of the hitch were after sifting through no less than four screens. The use of a smaller number of sieves in sifting must be specified in the normative documentation on the specific powder.

Installation for sifting, providing both a rotational movement of a set of sieves with sieve the powder and shake it with a uniform rate. The recommended modes of operation: rotation speed (31,5±1,5) rad/s (from 285 to 315 rpm), the frequency of shakes from 170 to 190 per minute.

Allowed to apply for the screening plant and screens in other modes of operation, providing the identity of the results obtained by the method.

Laboratory scales for General purpose — according to GOST 24104, or other scales, providing weighing accuracy up to 0.05 g.

A set of vessels with lids for collecting and weighing the sieved fractions or glossy paper.

5 TESTING

Clean and dry the selected sieve stack on the pallet by increasing the size of the holes. Weighted sample poured into the top sieve and cover with lid. Prepared a set of sieves with the sample powder placed in the apparatus for sifting. Include installation. Sieving is continued until the end of the screening or within the time specified in the normative documentation on the specific powder. The end time of sieving is achieved at a time when the amount of powder flowing during one minute through a sieve, retarding the largest mass changes by less than 0.1% of the mass of the sample for testing.

Allowed the sifting of the powder manually. Techniques of manual sifting must be specified in the normative documentation on the specific powder.

After sieving, the fraction of powder remaining on each sieve and on the pan is collected for weighing, beginning with the largest sieve size openings. The contents on each sieve gently shake to one side and pour lightly tapping on the sides of the sieve, on glossy paper or in a vessel for weighing. The powder stuck to the mesh or the sidewall of strainer, clean gently with a soft brush or brush to the next sieve with smaller holes.

Weigh each fraction powder with an error of less than 0.05 g. the weighing results of the fractions are rounded for samples with a mass of (100±1) g, to the first decimal place, and sample mass (50,0±0,5) g — up to the nearest multiple of five in the second decimal sign.

The test is considered valid if the sum of the masses of all fractions of powder not less than 98% of the mass of the sample for testing.

6 PROCESSING OF THE RESULTS

6.1 Mass fraction of fractions remaining on each sieve, and the fraction collected on the pan, , %, calculated by the formula

, (1)

where is the mass of this fraction of powder, g;

 — the sum of the masses of all fractions of powder,

The results of calculations are rounded to the first decimal place.

6.2 test Results recorded in a table. Mass fraction of fractions of the powder is less than 0.1% record the word «trace».


Table 1 — Example of a record of test results

7 TEST REPORT

The test report shall contain:

— data necessary for identification of the sample powder;

— the manner and mode of drying the powder, if it experienced not in the delivery condition;

— method by sieving characteristics of plants for screening and their modes of operation;

the duration of sieving;

the results of the test;

the designation of the present standard.

Annex a (recommended). International standard ISO 4497−83. THE METAL POWDERS. Determination of particle size by dry sieving

APPENDIX A
(recommended)

POWDER METAL

Determination of particle size by dry sieving

A. 1 Purpose and scope

This international standard specifies a method for determining the distribution of particle size metal powder dry sieving them into fractions.

The method is applicable to the dry metal powders without plasticizer and is not applicable to powders, the morphology which is significantly different from equiaxed, for example, lamellar type.

The method is not applicable to metallic powders, the particle size of which, or more of less than 45 microns.

A. 2 Links

ISO 565−90 Sieve test. Woven metal cloth, perforated metal plates and sheets produced by the electrolytic method. Nominal hole sizes

ISO 2591−1-88 Control sifting. Part 1. Methods using test sieves of woven metal cloth and perforated metal plates

A. 3 the method

The separation of the metal powder particle size fractions by shaking through a system of woven-wire sieves mounted in series in order of decreasing aperture sizes of the holes.

Weighing fractions retained on each sieve and the fraction passing through a very fine sieve.

A. 4 Instrument

A. 4.1 Set of grooved non-magnetic wire sieves with different nominal aperture size. Wire cloth each sieve shall be fixed in a metallic non-magnetic shell with a nominal diameter of 200 mm and a nominal depth of 25 to 50 mm.

Note — ISO 2591 sets the nominal depth of 50 mm.


Shells sit snug to each other. A set of sieves should be closed tightly with a lid and have a tray to collect the powder passed through the bottom sieve.

Calibration of sieves is carried out according to ISO 2591.

The aperture sizes of the test sieves should be chosen from the basic size of the sieves (R 20/3) according to ISO 565. If this is unacceptable, then the principal dimensions of the sieves can be replaced by one of the intermediate sizes (or R 40/3 R 20). The aperture sizes of the test sieves should choose such what should be the distribution of particle size of the test portion according to A. 7.

Note — By agreement between the supplier and the consumer can use an incomplete set of sieves.

A. 4.2 Installation for mechanical sieving, if necessary, according to A. 6.2.

A. 4.3 Scales, providing weighing up to 100 g with a precision of ±0.05 g.

A. 4.4 Soft brush.

A. 5 Preparation of test portions

A. 5.1 typically, the powder is tested in the delivery condition. If necessary, the powder is dried. If the powder is oxidized, drying is carried out in vacuum or in inert gas.

A. 5.2 Mass of the test portion should be approximately 100 g for powders with a bulk density of 1.50 g/cm. When the bulk density of the powder 1.50 g/cmand less mass of the test portion shall be approximately 50 g.

A. 6 test Procedure

A. 6.1 Selected set of test sieves must be equipped with a lid and a tray for the selection of the powder in order of increasing aperture size, with the sieve with the largest aperture should be on top. The test portion is placed in the top sieve and close lid tightly.

A. 6.2 Screening is performed manually or using a machine for mechanical screening.

Note — since different types of plants for screening will produce different results for the same powder and the same of sit, for a particular powder may be a correlation between different installations.

A. 6.3 Sieving continued until its termination or within the time agreed upon between the supplier and the consumer. Complete cessation of sifting occurs when the quantity passing through the sieve powder for 1 min (in accordance with ISO 2591) less than 0.1% of the maximum fraction of the test portion.

A. 6.4 After sieving weighed remaining on each sieve and on the pan fraction to the nearest 0.1 g if the mass of the test portion of 100 grams and to the nearest 0.05 g for the mass of the test portion 50 g. the Weighing start with the largest fraction and end up with a fraction on the pallet.

The fraction of powder remaining on each sieve is collected for weighing in the following way.

Remove the sieve from the nest. Sieve gently tilt, with a soft brush to collect its contents to one side and pour out on a sheet of glossy paper. A soft brush clean off the powder stuck to the sides and bottom of the sieve, the next smaller sieve. Scraping the sieve over glossy paper, flip on its side.

In the same way collect for weighing the fraction of the powder in the pan.

A. 6.5 the sum of the masses of all fractions shall not be less than 98% of the mass of the test portion.

A. 7 Processing of results

Weight fractions remaining on each sieve, and the fraction collected on the pan, should be expressed in percentage of the sum of the masses of all the fractions and recorded to the nearest 0.1 percent. Any faction, the percentage of which less than 0.1%, should be recorded as «traces».

As an example, given the following table of results.


Table A. 1

A. 8 test report

The test report shall contain the following information:

a) designation of this international standard;

b) all details necessary for identification of the test sample;

C) description of the drying process, if the powder was subjected to drying;

g) a method of screening and the characteristics of the device used for sifting;

e) duration of sieving;

e) the result obtained;

g) all operations not specified in this international standard or other international standards to which reference is made, or regarded as optional;

h) details of any phenomenon, which could affect the result.