GOST 18898-89

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  ГОСТ 18898-89

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

GOST 18898−89
(ISO 2738−87)

Group B59

STATE STANDARD OF THE USSR

POWDER PRODUCTS

Methods of determination of density, oil content and porosity

Powder products. Methods for determination of density, oil content and porosity

AXTU 1790

Valid from 01.01.91
to 01.01.95

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Academy of Sciences of the Ukrainian SSR

DEVELOPERS

V. N. Klimenko, A. E. Kushchevsky, V. S. Ageeva, O. M. Romanenko, L. D. Bernatsky

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 20.12.89 N 3899

3. The period of examination 1995

4. The standard fully complies with ISO 2738−87*
________________
* Access to international and foreign documents can be obtained by clicking on the link to the site shop.cntd.ru. — Note the manufacturer’s database.

5. REPLACE GOST 18898−73

6. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies methods for the determination of density, oil content and porosity of powder products, produced by powder metallurgy methods.

The essence of the methods consists in measuring the mass of products on the air and after closure of surface pores on the air and water with the subsequent determination of the extent, density, oil content and porosity.

The standard does not apply to products made of hard alloys, produced by powder metallurgy.

1. SAMPLING METHODS

1.1. The order of selection and the number of test samples is carried out in accordance with normative-technical documentation for powder products.

1.2. Samples for trials are the whole product or individual parts of a volume of at least 0.5 cm. If the volume of the products is less than 0.5 cmdetermination of density and porosity is carried out on multiple products with a total volume of more than 0.5 cm.

The density and porosity of the product is determined on the basis of mass and volume of all its parts, and for products with less than 0.5 cm — on the basis of the total mass and volume.

1.3. In determining the content of oil sample should be weighing more than 10 g and shall meet the requirements of claim 1.2.

1.4. For products weighing more than 0.5 kg are allowed to use as samples for testing parts in accordance with the requirements of the PP.1.2 and 1.3. The requirements for the selection of individual parts for testing must be specified in normative and technical documentation on specific product.

1.5. Before the test sample (the product) should be cleaned from adhering dirt, grease and other foreign materials. Products having cracks, holes, gouges and chipped edges, the tests are not allowed.

1.6. Before the test with the sample surface and remove excess oil by using a material, it is absorbent. You will not remove oil in the pores.

1.7. Removing oil from the surface of the sample is carried out according to GOST 24903.

1.8. The samples (products), whose volume can be calculated from measured primary dimensions must have tolerances on the dimensions with an accuracy not below 10-th class according to GOST 25347.

2. EQUIPMENT AND MATERIALS

2.1. Laboratory scales and others providing mass measurement of a product with the error not more than 0.01%.

2.2. Measuring tools (micrometer, caliper etc.), for measuring the linear dimensions of samples with errors according to GOST 8.051.

2.3. Extractor, Soxhlet with solvents for oils according to GOST 24903 or other devices for reliable oil extraction.

2.4. The device and the vessel for measuring the mass of the sample in air and in water in accordance with the devil.1−3. Wire devices shall be of non-corrosive material with a diameter of 0.25 mm. the Basket shall be made of the same wire with a minimum number of threads.

2.5. Distilled water according to GOST 6709, adding one or two drops of an aqueous solution of a wetting agent with a mass fraction of 0.1%.

2.6. Wetting agent OP-7 or OP-10 GOST 8433.

2.7. Oil according to GOST 20799 or oil with a known density and kinematic viscosity at 20 °C from 50 to 500 mm/s Oil for impregnation of the sample should not be mixed with water.

2.8. Pycnometer type ПЖ3 version 2 according to GOST 22524.

2.9. Thermometer type t-62А1−8 according to GOST 302, providing a temperature measurement of air and water with an error of not more than 0.5 °C.

2.10. Paraffin according to GOST 23683*.
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* On the territory of the Russian Federation the document is not valid. Valid GOST 23683−89. — Note the manufacturer’s database.

2.11. The medical vaseline by GOST 3582.

2.12. Benzyl alcohol according to GOST 8771*.
______________
* Probably, the error of the original. Should read: GOST 8751−72. — Note the manufacturer’s database.

2.13. Installation for vacuum impregnation of the sample with oil, generating a vacuum of at least 1 PA.

2.14. Xylene clean coal according to GOST 9949.

2.15. Filter paper according to GOST 12026.

2.16. The liquid repellent according to GOST 10834 or dilute (not less than 3%) of its solution in carbon tetrachloride.

2.17. Carbon tetrachloride according to GOST 4.

3. TESTING

3.1. The initial mass of the sample (the product) is weighed on the laboratory scales in the air with an error of not more than 0.01%.

3.2. Surface pore sample close by:

complete impregnation of the sample of oil;

partial impregnation of the sample with oil or paraffin;

samples coated by a film of vaseline, paraffin, hydrophobic liquid or its solution in carbon tetrachloride.

3.2.1. Complete impregnation of the sample oil is carried out by determination of the open porosity.

For this the sample vessel is filled with oil and placed in a chamber of a vacuum installation. Reduce pressure on the oil surface from 1 to 10 PA (7,5·10-10mm Hg.St.). Evacuation continues until, until the surface of the oil no longer comes up air bubbles. Then the pressure in the chamber of a vacuum installation equalize with atmospheric. The sample is left immersed in oil for at least the time VA — coumarouna. To ensure and verify the completeness of impregnation of the sample oil are repeated evacuation. To do this in a vacuum chamber to re-reduce the pressure from 1 to 10 PA. If air bubbles on the surface of the oil does not appear, I believe that impregnation of the sample occurred completely. The sample is removed from the oil after draining the oil purified in accordance with the requirements of paragraph 1.5. Allowed not to perform re-evacuation of the specimen in the oil, if in the normative-technical documentation for the particular products stated one-time vacuuming of the sample, ensuring its complete impregnation by the oil.

3.2.2. For partial impregnation, the sample is immersed in oil heated to a temperature of (65±5) °C and maintained until no longer stand out air bubbles. Cool the sample to room temperature, quickly moving it from hot in the room-temperature butter. Then the sample is removed from the oil after draining the oil meets the requirements of claim 1.5.

In case of partial impregnation with paraffin, the sample is dipped in melted paraffin and kept therein until the termination of allocation of bubbles. Then the sample is removed, placed on filter paper and cooled.

3.2.3. The film of paraffin on the sample obtained by immersion in a solution of paraffin (mass fraction 5%).

Preparation of the solution of paraffin is carried out according to GOST 9090*. After the termination of allocation on the surface of the sample air bubbles in the specimen is removed from the solution and dried to constant weight.
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* On the territory of the Russian Federation the document is not valid. Standards 9090−2000. — Note the manufacturer’s database.

Film hydrophobizing liquid get, immersing the sample in the liquid or in its diluted solution. Then the sample is removed and dried in a drying Cabinet for 20 minutes at the temperature (90−95) °C.

Vaseline is applied to the surface of the sample in a thin layer. The excess of vaseline is removed.

3.3. After impregnation with oil and close pores, as indicated in paragraph 3.2, the sample is weighed in air and in water with an error of not more than 0.01%. The sample and water should have a temperature of 15−30 °C. the Temperature of the water is measured with an error of not more than 0.5 °C. the Density of water at different temperatures is given in the Appendix. The sample in the water weighed in the balance with a stand, which set the vessel with distilled water.

When weighing the sample (product) in water is not permitted the formation of air bubbles on its surface. If bubbles appeared the sample is rejected or dried, is subjected to repeated treatment to close pores and again weighed in air and in water. After weighing in water with the sample surface with filter paper to remove the moisture and re-weighed it on the air.

If the sample mass is not changed, the weighing operation is complete. If you increase the weight after re-weighing in the air sample is rejected or subjected to repeated handling.

To determine the sample volume using the pycnometer filled with distilled water. The use of other liquids with known density.

First weighed on a laboratory scales and sample separately pycnometer filled with water to the top holes of the tube and thermostated at 20 °C.

Then the sample is placed in a pycnometer with water, thermostatic at a temperature of 20 °C and removed by shaking the air. The water level in the pycnometer is brought to the upper opening of the tube. Then the pycnometer with the sample is weighed.

Using the calculation method of determining the volume of the samples meet the requirements of section 1.7, measured according to GOST 8.051.

4. PROCESSING OF THE RESULTS

4.1. The density of the sample (product), not oiled, (), g/cm, is calculated by the formula

,

where or ;

 — initial mass of sample for test, not impregnated with oil, g;

 — weight of sample for test after oil extraction and drying, g;

 — sample volume, cm.

The volume of the sample (), cm, when using a weighing device in accordance with the devil.1−3, calculated by the formula

,

 — the sample mass with closed pores and restraint in hell.1−3, suspended in air, g;

 — the sample mass with closed pores and restraint in hell.1−3, suspended in water, g;

is the density of water corresponding to the temperature of weighing, g/cm;

The volume of the sample (), g/cm, when used for weighing the pycnometer is calculated by the formula

,

where is the total mass weighed individually (or in one step) of a sample of closed cell and the pycnometer with liquid, g;

 — weight of pycnometer with sample and liquid with the closed impregnation of the pores, g;

 — the density of the liquid in the pycnometer, corresponding to a temperature of weighing, g/cm.

Allowed to determine the amount of samples , measurements of their basic dimensions.

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

4.2. The relative density of the sample (of product) () percentage calculated by the formula

,

where is the density of the sample, calculated according to claim 4.1 g/cm;

theoretical density of compact material of a given composition, g/cm.

4.2*. The mass fraction of oil in the sample (the product) () percentage calculated by the formula

,

where is the initial mass of the sample, saturated with oil, g;

 — the sample mass after oil extraction and drying,
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* Numbering corresponds to the original. — Note the manufacturer’s database.


The volume fraction of oil () in the sample is calculated in percent to the first decimal place according to the formula

,

where is the density of extracted oil, g/cm;

 — the sample volume is calculated according to claim 4.1 g/cm.

The volume fraction () of the open pores of the sample saturated with oil, calculated in percent to the first decimal place according to the formula

,

where is the density of oil used for complete impregnation of the sample in the determination of his apparent porosity g/cm;

 — the mass of the fully oil-impregnated sample weighed in the air,

4.4. The open porosity of the sample () is calculated in percent to the first decimal place according to the formula

,

where is the mass of a fully oil-impregnated sample weighed in air;

or ;

 — initial mass of sample, saturated with oil, g;

 — the sample mass after oil extraction and drying, g;

is the density of oil used for complete impregnation of the sample, g/cm;

 — the sample volume is calculated according to claim 4.1 g/cm.

The open porosity determined for the samples (products), total porosity exceeding 10%.

The total porosity of the sample () is calculated in percent to the first decimal place according to the formula

,

where is the density of the sample, calculated according to claim 4.1 g/cm;

theoretical density of compact material of a given composition, g/cm.

The closed porosity in percent is calculated as the difference between total and open porosity .

4.5. The test results recorded in a Protocol containing:

the name of the product;

the material grade of the product;

the characteristics of the sample (information about oiling, the type and conditions of receipt of the sample, its weight, etc.);

the method of closure of surface pores of the sample;

the oil used for thorough impregnation;

test temperature;

the results of the test;

the testing date.

APP. The dependence of water density from temperature

APP