ASTM B962-15 pdf download.Standard Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes’ Principle.
6. Interferences 6.1 A gain in mass when a test specimen is immersed in water is an indication that the specimen contains surface- connected porosity. Unsealed surface porosity will absorb water and cause the calculated density values to be higher than the true value. 6.2 Test specimens that contain surface-connected porosity shall be oil impregnated or have the surface-connected porosity sealed by some other means prior to their immersion in water.
7. Apparatus 7.1 Analytical Balance—Precision single-pan balance that will permit readings within 0.01% of the test specimen mass. See Table 1.
7.2 Water Container—A glass beaker or other suitable transparent container should be used to contain the water. N OTE 1—A transparent container makes it easier to see air bubbles adhering to the test specimen and specimen support when immersed in water. N OTE 2—For the most precise density determination, the water con- tainer should be ofa size that the level ofthe water does not rise more than 0.10 in. (2.5 mm) when the test specimen is lowered into the water.
7.3 Water—Distilled or deionized water to which 0.05 to 0.1 volume percent ofa wetting agent has been added to reduce the effects of surface tension. N OTE 3—Degassing the water by evacuation, boiling, or ultrasonic agitation helps to prevent air bubbles from collecting on the test specimen and support when immersed in water.
7.4 Test Specimen Support for Weighing in Water—Two typical arrangements are shown in Fig. 1. The suspension wire may be twisted around the test specimen or the test specimen may be supported in a wire basket that is attached to the suspension wire. For either arrangement, a single corrosion- resistant wire—for example, austenitic stainless steel, copper, or nichrome—shall be used for the basket and suspension wire. The maximum recommended diameter of suspension wire to be used for various mass ranges is summarized in Table 2. N OTE 4—For the most precise density determinations, it is important that the mass and volume of all supporting wires immersed in water be minimized. 7.5 Oil for Oil-Impregnation—Oil with a viscosity of 20 to 65 cSt or 100 to 300 SSU (20 × 10 -6 to 65 × 10 -6 m 2 /s) at 100 °F (38 °C) has been found to be suitable. 7.5.1 In the case ofoil-impregnated bearings, make an effort to match the oil that was originally used to impregnate them. 7.6 Vacuum Impregnation Apparatus—Equipment to im- pregnate the part or test specimen with oil. 7.7 Thermometer—A thermometer with an accuracy of 1.0 °F (0.5 °C) to measure the temperature of the water.
8. Preparation of Test Specimens
8.1 The mass of the test specimen shall be a minimum of 1.0 g. For small parts, several parts may be combined to reach the minimum mass.
8.2 Thoroughly clean all surfaces of the test specimen to remove any adhering foreign materials such as dirt or oxide scale. Take care with cut specimens to avoid rough surfaces to which an air bubble may adhere. A100-grit sanding or abrasive grinding is recommended to remove all rough surfaces. 9. Procedure 9.1 The part or test specimen, the analytical balance and surrounding air shall be at a uniform temperature when weighing is performed.
9.2 For the most precise density determinations, duplicate weighings should be made for all mass measurements. Adjust the analytical balance to zero prior to each weighing. Average the mass determinations before calculating the density.
9.3 For improved repeatability and reproducibility, verify the analytical balance periodically with a standard mass that is approximately equal to the part or test specimen mass.
9.4 This standard contains three separate test methods; determination of green density, determination of sintered density, and determination of impregnated density. Each is detailed in the following sections. Determination of Green Density
9.5 This procedure is used to determine the green density of PM parts and test specimens. 9.5.1 Determine the mass ofthe green part or test specimen. This is mass A. This and all subsequent weighings shall be to the precision stated in Table 1.
9.5.2 Oil impregnate the green part or test specimen as follows: Preferred Procedure 9.5.3 Immerse the part or test specimen in oil at room temperature. 9.5.4 Reduce the pressure over the sample to 1 psi (7 kPa) or less for 30 minutes, then increase the pressure back to atmospheric pressure and keep the sample immersed for at least 30 minutes. 9.5.5 Remove excess oil by wiping gently with an absorbent, lint-free material. Take care not to extract oil absorbed within the part or test specimen. 9.5.6 Do not place or store parts on porous surfaces such as paper, cloth, or cardboard as these will absorb oil.ASTM B962 pdf download.