GB/T 21354-2008 English PDF (GBT21354-2008)

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GB/T 21354-2008: Powders -- Determination of tap density
GB/T 21354-2008
Powders.Determination of tap density
ICS 71.060.01
G10
National Standards of People's Republic of China
GB/T 21354-2008/ISO 3953..1993
General method for determination of tap density of powder products
(ISO 3953..1993, Metalogic Devices-Determination Information, IDT)
2008-01-11 released
2008-07-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Issued by China National Standardization Management Committee
Foreword
This standard is equivalent to the use of ISO 3953..1993 "Determination of tap density of metal powder" (Third Edition) (English version).
This standard was drafted according to ISO 3953..1993 "Determination of tap density of metal powders".
This standard was proposed by China Petroleum and Chemical Industry Association.
This standard is under the jurisdiction of the National Chemical Standardization Technical Committee Inorganic Chemical Branch (SAC/TC63/SC1).
This standard was drafted by. Tianjin Chemical Research and Design Institute, Qingdao Entry-Exit Inspection and Quarantine Bureau.
Drafters of this standard. Li Guangming, Zhao Zuliang, Wang Jun.
GB/T 21354-2008/ISO 3953..1993
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). Set international standards
The work is usually done by ISO technical committees. Each member group has the right to participate if it is interested in a project established by a technical committee
The work of the committee. International organizations (official or unofficial) that maintain contact with ISO can also participate in related work. In electrical engineering
In terms of technical standardization, ISO maintains close cooperation with the International Electrotechnical Commission (IEC ).
The draft international standards adopted by the technical committee shall be decided by voting by member groups. Publishing as an international standard requires membership of the group
75% voted through.
International standard ISO 3953 "Sampling and test methods for powders (including hard metals)" by Technical Committee ISO /T C119, Powder Metallurgy
Developed by subcommittee SC2.
The third edition abridged and modified Table 2 in the second edition (ISO 3953. 1985).
GB/T 21354-2008/ISO 3953..1993
General method for determination of tap density of powder products
1 Scope
This standard specifies the method for measuring the tap density, that is, the powder in the container is tapped under certain conditions.
2 Principle
Use a vibrating machine to vibrate the specified amount of powder in the container until the volume of the powder no longer decreases. The mass of the powder divided by the volume gives
The result is the tap density.
It can also be tapped by hand.
3 Symbol
See Table 1.
Table 1
Symbol description unit
ρt
Tap density
Powder quality
Volume after powder compaction
g/cm3
cm3
4 Instruments
4.1 Balance
The weighing range and accuracy should meet the requirements of Table 2.
Table 2
Tap density ρt/(g/cm
≥1
＜ 1
100 ± 0.5
50 ± 0.2
＞ 7
2 ～ 7
0.8 ～ 2
< 0.8
100 ± 0.5
50 ± 0.2
20 ± 0.1
10 ± 0.1
4.2 Glass measuring cylinder
4.2.1 The calibration volume is 100cm3, the height of the scale area is about 175mm, the sub-scale is 1cm3, and the measurement accuracy can reach ± 0.5cm3.
4.2.2 The calibration volume is 25 cm3, the height of the scale area is about 135 mm, and the sub-scale is 0.2 cm3.
4.2.3 A measuring cylinder with a nominal volume of 25 cm3 is mainly used for products with a tap density higher than 4 g/cm3. The tap density of the powder is
Can also be used at low times.
4.3 Vibration instrument
The bottom of the instrument is required to be strong and able to withstand the vibration of the measuring cylinder. Vibration should be carried out under sealed conditions to avoid any loosening of the surface layer.
The stroke should be 3mm, and the vibration frequency should be between 100 times/min and 300 times/min. The vibration instrument is shown in Figure 1.
You can also use a manual method. use a thick rubber pad (size about 100mm × 100mm × 5mm).
GB/T 21354-2008/ISO 3953..1993
Picture 1
5 samples
5.1 The sample quality required for each test is shown in Table 2.
5.2 In general, the test sample should maintain its original form, and in some cases the sample needs to be dried. However, if the sample is oxidizable
It should be dried in vacuum or inert gas. If the sample contains volatile substances, it cannot be dried.
5.3 The test is carried out in 3 steps.
6 Analysis steps
6.1 Cleaning
Use a brush to clean the glass graduated cylinder (4.2), or use a solvent (such as acetone) if necessary. If a solvent is used, the amount used again
Wash thoroughly before the tube. It must be dried before use.
GB/T 21354-2008/ISO 3953..1993
6.2 Weighing
Weigh the sample with the balance (4.1) according to the sampling amount specified in Table 2, accurate to 0.1g.
6.3 Determination
Place the sample in the graduated cylinder. Note that the sample should be flat. Place the measuring cylinder on the vibrating instrument (4.3) and vibrate the measuring cylinder until the sample body
The product no longer decreases by 1).
It is also allowed to use the following method of tapping. take the measuring cylinder by hand and vibrate on the thick rubber pad (4.3) until the sample volume no longer decreases
until.
Before the end of this process, the tapping should be light to avoid loosening of the sample surface 2).
6.4 Reading
Read the volume of the surface that has reached the level after tapping. If the surface is uneven, read the average value of the highest and lowest points on the surface after tapping, as
Vibration volume. When using a 100 cm3 measuring cylinder, the final volume read is close to 0.5 cm3. If a 25 cm3 measuring cylinder is used, the final
The volume value is close to 0.2 cm3.
7 Result calculation
The powder tap density is calculated as follows.
In the formula.
ρt --- the value of tap density, the unit is gram per cubic centimeter (g/cm
3);
狏 --- the value of the sample volume after the compaction, the unit is cubic centimeters (cm3).
Take the arithmetic average of the three test results as the measurement result. When the tap density does not exceed 4g/cm3 (including 4g/cm3), it is accurate to
0.1g/cm3; when it is greater than 4g/cm3, it is accurate to 0.2g/cm3.
1) In the actual process, the minimum number of times that the volume does not change should be determined. For all tests of the same powder, the graduated cylinder must pass more than 2N times
Shock. Unless experience shows that the specified number of times (not less than N) vibration, the results are reliable and satisfactory. For fine metal powder, it has been issued
Now, 3,000 vibrations can meet all particle size requirements.
2) In general, both mechanical and manual methods can achieve parallel results. However, for powders with very low tap density or very fine powders, these two
The results obtained in this way are significantly different.
GB/T 21354-2008/ISO 3953..1993