1 Scope
This document specifies a method for the determination of the density of liquid metals.
This document applies to the determination of the density of liquid metals in the range from room temperature to 300 °C. The density determination of molten salts and metal melts above 300 °C can also be used with reference.
2 Normative references
The contents of the following documents constitute essential provisions of this document through the normative references in the text. Among them, note the date of the reference documents, only the date of the corresponding version applicable to this document; do not note the date of the reference documents, the latest version (including all the revision of the list) applicable to this document.
GB/T 1423 Test methods for the density of precious metals and their alloys
GB/T 4339 Determination of characteristic parameters of thermal expansion of metallic materials
GB/T 8170 Rules for numerical modifications and the representation and determination of limit values
3 Terminology and definitions
There are no terms and definitions that need to be defined in this document.
4 Principles
Based on Archimedes' principle, the mass of a weight of known mass is measured after immersion in a liquid metal to obtain the buoyancy of the weight in order to calculate the density of the liquid metal, as illustrated in Figure 1.
5 Apparatus
5.1 Resistance furnace: at the set temperature, the temperature stability of the furnace should not exceed ±1°C.
5.2 Thermocouple: Grade 1 industrial thermocouple, should be used to resist corrosion of liquid metal stainless steel or ceramic protection tube.
5.3 Inert gas: Nitrogen or argon with a volume fraction of not less than 99.99%.
5.4 Crucible: at the test temperature without any dissolution or reaction with the sample, preferably made of metallic molybdenum, graphite, quartz, alumina ceramics, etc.
5.5 Weight: at the test temperature without any dissolution or reaction with the sample, the mass should be 10g~100g, the density should be not less than 10g/cm3, should be made of molybdenum, tantalum, tungsten and other materials.
5.6 Suspension wire: at the test temperature does not dissolve or react with the sample, the diameter should be no greater than 0.2mm, should be made of molybdenum wire.
5.7 electronic balance: 0.1mg division value.
6 Samples
6.1 liquid sample: the volume should be not less than 50mL, and can be submerged in heavy hammer. The surface oxide layer should be removed before the test.
6.2 Solid samples: made of particles or small pieces of solid for sample loading, the volume of the sample after melting should be not less than 50mL, and can submerge the hammer.
7 Test procedure
7.1 Parallel tests
Two independent measurements shall be taken and averaged.
7.2 Determination
7.2.1 Determine the density ρ0 of the weight at room temperature in accordance with the method described in GB/T 1423 and, if necessary, the coefficient of linear thermal expansion of the weight material in accordance with the method described in GB/T 4339.
7.2.2 The sample is loaded into the crucible, the temperature measuring thermocouple is placed in the sample and the crucible is placed in the furnace chamber.
7.2.3 The weight is suspended from the electronic balance by a suspension wire and placed directly above the sample.
7.2.4 An inert gas flow rate of 0.1L/min~1L/min is introduced into the furnace chamber for at least 30 minutes to remove the air from the chamber; the inert gas flow rate is maintained at 0.1L/min~0.2L/min during the test.
7.2.5 Heat the sample to the test temperature and maintain a constant temperature for at least 30 minutes.
7.2.6 Measure the weight m0 of the weight in the inert gas.
7.2.7 The weight is completely immersed in the sample without any contact between the weight and the bottom or wall of the crucible.
7.2.8 After the balance reading has stabilised, record the weighing weight m1 of the weight in the sample.
8 Processing of test data
8.1 When the test temperature is not higher than 50 °C, the density of the sample is calculated according to formula (1) and is recorded as ρ. The value is expressed in grams per cubic centimetre (g/cm3).
8.2 When the test temperature is higher than 50°C, the density of the sample is calculated according to equation (2).
9 Precision density
9.1 Repeatability
The difference between two measurements of the same sample by the same operator, in the same laboratory, with the same set of equipment, at the same test temperature, shall not be greater than 2.0% of the average value.
9.2 Reproducibility
The difference between measurements of the same sample by different operators, in different laboratories, with different equipment, at the same test temperature, shall be no greater than 3.0% of the mean value.
10 Test report
The test report shall give, as a minimum, the following:
--- the number and description of the sample;
---test temperature;
---Results;
---The number of this document.
Foreword
1 Scope
2 Normative references
3 Terminology and definitions
4 Principles
5 Apparatus
6 Samples
7 Test procedure
8 Processing of test data
9 Precision density
10 Test report
