This standard specifies the method for determining the total oxygen content of no more than 2% (mass fraction) in metal powders by high-temperature reduction-extraction. This standard is applicable to various metals, alloys, carbides (hard alloys) and mixed powders of components that are volatile under the test conditions. It can also be used to determine the total oxygen content in sintered metal materials. The sample can be in powder form. The powder is analyzed as supplied. This method is not suitable for powders containing lubricants or binders. If the sample contains lubricants or binders, this method can only be used if a method is first used to completely remove these substances without affecting the oxygen content. GB/T 5158.4-2001 Determination of total oxygen content in metal powders Reduction-extraction method GB/T5158.4-2001 Standard download decompression password: www.bzxz.net

GB/T5158.4—2001
This standard is formulated in accordance with the international standard ISO44914:1989 (E) ≤Determination of oxygen content of metal powder by reduction method Part 4: Determination of total oxygen content by reduction-extraction method". The technical content of this standard is equivalent to that of IS044914:1989 (E). Appendix A of this standard is a reminder appendix. This standard is proposed by the State Bureau of Nonferrous Metals Industry. This standard is under the jurisdiction of the China Nonferrous Metals Industry Standard Metrology and Quality Research Institute. The drafting unit of this standard is the Institute of Powder Metallurgy of Central South University. The main drafters of this standard are Xiao Cai, Liao Jiqiao, and Liu Dongwen. 2
GB/T 5158.4—2001
ISO/IEC Foreword
The International Organization for Standardization (ISO) is a worldwide alliance of national standardization bodies (ISO member bodies). The development of international standards is usually carried out through ISO technical committees. Any member group interested in a particular area of ​​expertise for which a technical committee has been established has the right to participate in the committee. Official and non-official international organizations in liaison with ISO also participate in this work. ISO works closely with the International Electrotechnical Commission (IEC) on electrical technology: draft international standards adopted by the committee are circulated to the member groups for voting, and publication as international standards requires approval by at least 75% of the member groups voting.
International Standard ISO 44914 was developed by ISO/TC 119 Powder Metallurgy Technical Committee. ISO 4491 consists of the following parts, with the general title: Metal powders - Determination of oxygen content by reduction method. Part 1: General
Part 2: Mass loss on hydrogen reduction (hydrogen loss) Part 3: Oxygen reducible by hydrogen
Part 4: Determination of total oxygen content by reduction-extraction method Annex A to Part 4 of ISO 4491 is for reference only. 122
GB/T 5158.4—2001
ISO Introduction
The determination of oxygen content in metal powders is important in many areas of powder processing. The total oxygen content is not given in the standard methods described in Parts 2 and 3 of this standard because some oxygen-containing components are not reduced by hydrogen.
Therefore, a standard method for the determination of total oxygen content is required. The most commonly used method for the determination of total oxygen is the reduction-extraction method. It can be determined using instruments available on the market that work on a variety of different extraction and measurement principles. It should be emphasized that the analytical results depend on the equipment used and the experimental parameters selected. However, as pointed out in Clause 36 of this standard, for a given type of metal powder, reproducible and accurate results can be obtained by selecting the best test conditions using any commercially available instrument designed for testing that metal powder. It is not possible to standardize one or more specific instruments. However, the basic points of the recommended metal powder analysis procedures are worthwhile. Note: The reduction extraction method can also be used for nitrogen determination. Some instruments can determine oxygen and nitrogen contents simultaneously. However, this standard does not cover the determination of nitrogen. 1
1 Scope
National Standard of the People's Republic of China
Metallic powders-Determination of total oxygen content by reduction-extractian
Reduction-extraction method
Metallic powders-Determination of total oxygen content by reduction-extractian
GB/T5158.4—2001
idt ISO 4491-4.1989(E)
This standard specifies the method for the determination of the total oxygen content of not more than 2% (mass fraction) in metal powder by high temperature reduction-extraction. This standard is applicable to various metals, alloys, carbides (hard alloys) and mixed powders with no volatile components under the test conditions. It can also be used to determine the total oxygen content in sintered metal materials. The sample can be in powder or compacted form, and the powder is analyzed as supplied. This method is not suitable for powders containing lubricants or binders. If the sample contains lubricants or binders, it is only necessary to first collect the sample. This method can only be used if these substances can be completely removed by a certain method without affecting the oxygen content. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard by reference in the technical standards. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision. Parties using this standard should investigate the possibility of using the latest versions of the following standards. ISO44911:1989 Metal powders-Determination of oxygen content by reduction method Part 1: General 3 Principle
The sample is placed in a high-temperature graphite crucible and heated under vacuum or inert atmosphere. The oxygen in the sample is converted into carbon oxides. These carbon oxides are extracted and completely converted into CO or C (), which can be determined by appropriate gas analysis methods. The methods commonly used in the determination of total oxygen content in practice have the following characteristics: a) The environment of the reaction chamber: vacuum or inert gas flow (nitrogen, argon, nitrogen) b) Ink crucible: single (such as only used for the determination of one sample) or multiple (such as the same crucible for the analysis of consecutive samples).
c) Reaction medium:
Solid, for example, the sample is poured into a graphite crucible, and the metal to be tested has not melted, that is, it has already undergone a reduction reaction while it is still in the solid state: Metal bath, for example, in order to accelerate the reduction reaction of some metals, a fusible metal (such as platinum, tin, iron, nickel) bath that can dissolve both the carbon and gold chips in the sample can be prepared first. d) Heating:
Continuous heating, for example, the sample is placed in a graphite crucible that has been preheated to the reaction temperature, and the reduction reaction lasts for a fixed time, about a few minutes.
Pulse heating, for example, the cold crucible containing the sample is placed in a furnace and heated, and a high-power pulse is used for a few seconds. The reduction reaction proceeds very quickly at the peak temperature (up to 3000°C) generated by the pulse. e) Determination of oxygen:
Detection of CO or C (), there are several methods that can be used. In both cases, a chemical conversion device is used to completely convert the oxygen being measured into CO or CO: Commonly used analytical methods are: volumetric method (detection of CO);
chromatographic method (detection of C));
infrared absorption method (detection of C());
thermal conductivity method (detection of C) and (O,):
coulometry (detection of (,).
4 Instruments and materials
GB/T 5158. 4- 2001
An apparatus suitable for determining the oxygen content of metal powders consists of the following main components: a) a graphite, made of high purity graphite; h) a device for degassing graphite at high temperature; c) a device for sampling and degassing in vacuum or inert atmosphere at room temperature; d) a gas extraction device matched to the predicted temperature cycle; d) a water removal and purification device; f) a detection device for determining C) or CO,. The materials required will depend on the type of equipment used, such as high purity carrier gas (ammonia or argon). If necessary, the detection device should be calibrated with high purity gases CO, CO, or certified metal reference standard samples. 5 Samples
Weigh two samples for analysis. Before the sample enters the instrument, the following methods can be used to prepare the sample: a) weigh the sample directly and put it into the degassed medium. b) take an appropriate amount of powder sample in a small cylindrical mold, without adding any lubricant or binder, uniaxially press at a pressure of 100mV/mm2 to 200mN/mm, and measure the mass of the pressed embryo. ) take an appropriate amount of powder sample and pack it into a small capsule made of high-purity platinum, nickel or iron-nickel foil of known mass, and then weigh the sample and capsule. The oxygen content of the foil can be measured in advance. d) if the sample has been formed, take a suitable piece of the sample and weigh it as the sample. The sample is weighed accurately to 0.1Ig. If the metal foil capsule is used only to facilitate the input of the sample, the mass of the capsule should be as light as possible. However, when the material used to make the case (a certain metal) can be used to form a metal bath required for the extraction of a certain gas: the mass of the capsule should be determined according to the mass ratio of metal bath to sample recommended for a specific analysis.
When the graphite capsule and the metal bath are used for several consecutive analyses, the metal should be degassed before the gas is extracted again. The mass ratio of metal bath/sample should be kept greater than the recommended minimum. If necessary, metal chips are added periodically after the metal bath is degassed. The choice of sample amount depends on the sensitivity of the instrument and the expected oxygen content. Usually, the sample amount is selected between 0.1g and 1g. 6 Steps
6.1 General
For the reasons stated in the introduction, for the various types of instruments available and the various types of metals, alloys and carbides (hard dielectrics) to be measured,It is not practical to specify the conditions for the determination of oxygen. It should be noted that, especially when the reduction reaction is carried out in the solid phase and heating is continued, the reaction may be slow and the time for the oxide reduction to be complete will depend on the oxygen content. For testing a particular type of material and a given oxygen content range, it is recommended to determine the best conditions through preliminary tests. Generally, a series of (conditions) tests are carried out on the same sample. The degree of reduction is increased (temperature is increased or reaction time is prolonged) until the oxygen content test value reaches a maximum and remains constant. Other test conditions (or parameters) (such as the use of metal baths) can also be changed accordingly. It is particularly recommended to use certified reference materials of the same type as the sample to verify or calibrate the selected working conditions. 6.2 Blank test and calibration
GB/T 5158. 42001
Usually, the blank test is carried out under the same test conditions as those selected for the determination of the sample, but without the sample. If necessary, calibrate according to the instructions provided by the instrument manufacturer to verify whether the instrument is in normal working condition. Generally, pure gas (CO, CO,) or standard materials with verified oxygen content are used for calibration.
6.3 Test
Carry out the test according to the instrument manual and the selected test conditions (see 6.1). Appendix A lists some examples of metal powder reduction conditions.
7 Expression of results
7.1 Permissible difference
The difference between two measurements shall not exceed the maximum permissible difference listed in Table 1. 7.2 Final result
Report the arithmetic mean of the two measurements and make rounding according to 1. Table 1
Single mass fraction
>0. 003~0, 01
20. 01~0. C2
>0. 02~-0. 05
-, [5-- 0. 1
0. 1-~0. 2
-C. 2·0. 5
>0. 5 ~1. 0
1. tt-2. 0
Test report
The test report shall include the following information:
a) This standard;
b) Details required for identification of the specimen;
c) Relevant methods for removal of lubricants and adhesives; d) Model of equipment used:
Maximum allowable end difference between two determination results
20% of the average value
105% of the average
10% of the half mean||tt ||5% of the mean
5% of the mean
5% of the mean
5% of the mean
5% of the meanbzxZ.net
5% of the mean
e) relevant test conditions (temperature, time, whether a metal bath or a metal capsule is used, etc.); f) the results obtained (see 7.2);
g) operations not specified in this standard;
h) any circumstances that may affect the test results. 126
The results are accurate to
Metal powders
Iron, steel
Titanium, zirconium and hafnium
Molybdenum and tungsten
Silver and knob
Hard alloy mixed warp
GB/T5158.4 -2001
Appendix A
(Suggestive Appendix)
Examples of conditions for extracting oxygen from metal powders
Reaction medium
Especially requires gold-fluorine bath or platinum
Platinum capsule and platinum bath
No metal bath required
Nickel-tin bath
No metal bath required
Fe-tin and tin ink
Metal bath/sample
Minimum mass ratio
Temperature 1
1) These temperatures are used for continuous heating (time is 1min~-10min, depending on the actual value of (volume content). When using a pulse furnace for extraction, it is usually carried out at above 3000℃. Road belt, 1#--20% is sufficient for complete reaction 127
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