GB/T24525-2009 Carbon resistivity tester

BEST-310 carbon resistivity tester
One Description:
The four terminal testing method is used to measure the electrical conductivity of carbon materials, graphite and other block shaped rod-shaped and powder materials at room temperature. Constant current, automatic current mode, 4.3-inch LCD display, displaying data such as current, voltage, temperature, resistivity, conductivity, resistance, etc. Optional: PC software to obtain test data maps and reports. Choose testing fixtures according to different product shapes

II Scope of application:
Suitable for material research in carbon plants, coking plants, petrochemical plants, powder metallurgy plants, universities, and research departments
III Reference standard:
Methods for testing carbon materials for aluminum - Part 2: Determination of room temperature resistivity of cathode carbon blocks and pre baked anodes GB/T6717, GB/T 24525-2009, YS/T63.2 Methods for determining resistivity of carbon materials; ISO 11713-2000, YS/T63.2-2005, and YS/T 64-1993 standard methods test the electrical resistivity of cathode carbon blocks, pre baked anodes, anode paste cathode paste, and carbon products at room temperature.
The resistivity value of carbon material products is an important parameter for evaluating the electrode quality of carbon products and controlling and supervising the process in carbon product processing.
The sensitivity of measuring resistance reaches 0.01 μ Ω The test current can reach 10A
4 Parameter data/index
1. Voltage range: 2mV.20mV.200mV.2V
Resolution: 0.1uV, 1uV, 10uV, 100uV
Range error: 2mV range: 0.1% reading+6 words
20mV. 200mV. 2V gear: 0.1% reading+2 words: 20mV. 200mV. 2V. accuracy: 0.1%
2 DC constant current sources: Output: 100uA.1mA.10mA.100mA.1A.10A
Error: 100uA.1mA.10mA.100mA: 0.1%;
:1A，10A ： 0.15%
3. Measurement range: Carbon length: 1.6m-2m; Carbon diameter: 100mm -600mm
Resistance: 2 × 10-8-20k Ω· cm; Resistance: 0.01 μ Ω -20k Ω;
4. Resistance resolution: 0.01 μ Ω
5. Display: 4.3-inch LCD screen, direct reading resistance value, resistivity, conductivity, temperature, current, voltage and other data
6. AC power supply: 220 ± 10% 50HZ/60HZ
Supporting solution: Solve the measurement of various material states - solid, liquid, gas, granular resistance, resistivity, conductivity
Measurement method for electrical resistivity of carbon materials
This standard specifies the principles, instruments and equipment, test procedures, and allowable errors for measuring the resistivity of carbon materials. This standard is applicable to the determination of electrical resistivity of carbon and graphite products at room temperature, with normative references
The clauses in the following documents become clauses of this standard by reference. Any referenced document with a specified date shall not be subject to any subsequent amendments (excluding errata) or revisions to this standard. However, parties to agreements based on this standard are encouraged to explore the possibility of using newer versions of these documents. Any referenced document without a date shall be subject to the latest version of this standard.
GB/T 1427 Sampling Method for Carbon Materials
GB/T 8170 Numerical rounding rules and representation and determination of limit values 3 principles
Electrical resistivity is a property that represents the resistance of a material when passing through an electric current. It is numerically equal to the resistance value of a conductor with a length L of 1m and a cross-sectional area S of 1m, denoted as p. According to Ohm's law and the characteristics of conductors, the following formula can be derived:;
In the formula.
P - the resistivity of a conductor, measured in micro ohmmeters (μ Qm); U - voltage drop at both ends of a conductor, measured in millivolts (mV); -The current intensity through a conductor, measured in amperes (A); S - cross-sectional area of the specimen, measured in square millimeters (mm2); L - The length of a conductor, measured in millimeters (mm).
Note: The results should be rounded to one decimal place, and the values should comply with the regulations of Building GN/T s170.
If the sample is processed into a certain geometric shape, S/L is a constant. Adjust the current intensity passing through the sample to be numerically equal to S/L, so that the voltage drop at both ends of the sample is numerically equal to the resistivity of the sample. The resistivity value can be directly read out by a digital voltmeter,
Laboratory specimen determination 4.1 Instrument and equipment
Pressure testing machine with a range of not less than 20 kN.
Vernier caliper: measuring range (0-200) mm, accuracy 0.02 mm. Micrometer; The measurement range is (O~25) mm, (25~50) mm, and the accuracy is 0.0l mm.
The stroke range of the graphite product testing rack 1 is (110~190) mm; The contact is conical and made of yellow. As shown in Figure 1.
Carbon product testing rack, as shown in Figure 2.
Electrical resistivity tester; As shown in Figure 3. The output accuracy of the constant current source is ± 0.1%, and the output current is not less than 10A. The accuracy of the digital voltmeter is ± 0.1%, and the measurement accuracy of the entire instrument is ± 0.5%.
Blast drying oven: equipped with an automatic temperature control device, capable of maintaining a temperature of (105~110) ℃.
Determination of electrical resistivity of graphite products
The sample shall be sampled and processed according to GB/T 1427, including:
(1) Sample size for electrodes with a diameter of 500mm or more: diameter of 30mm ± 0.1mm x length of 180mm ± 0.2mm; (2) Three samples are taken for each internal graphitization protection (LWG) protection.
Experimental steps
The sample is dried in a blast drying oven at (105-110) ℃ for 2 hours, and then cooled to room temperature in a dryer for later use.
Accurately measure the diameter and length of the sample,
Select the appropriate length of the measurement section △ L on the sample, generally taking L as 1/2~1/3 of the sample length, with a measurement error of ± 0.5%
Correct and adjust the resistivity tester so that the current intensity passing through the sample is numerically equal to S/AL. Place the sample on the testing rack (Figure 1) and clamp it tightly. Press the current pressure button to read the resistivity value of the AL section, and then press the conversion switch to read the resistivity value of the AL section on the other side. Reverse the position of the two ends of the sample or change the direction of the current to repeat the test, and take the average of the four measurement results.
Determination of electrical resistivity of carbon products
The sample shall be sampled and processed according to the provisions of GB/T 1427.
Experimental steps
Clamp the test stand (Figure 2) onto the specimen and place it on the pressure testing machine, maintaining a pressure of 6.3 MP at both ends of the specimen. Press the current button 4.3.2.6 to read the electrical resistivity value of the AL section, and then press the switch in different directions to read the electrical resistivity values of the four directions
Resistance value, take the average of four measurement results.
On site measurement of graphite electrode products using 5.1 instruments and equipment
The fluctuation of stabilized DC power supply 1 is not greater than 1%.
Electrical resistivity tester; Request to see
Potential contact 1 has a conical shape and is made of a yellow pot
Specimen
The cross-sectional area must be uniform, the sample must not have obvious defects, and there must be no scale buildup on the surface.
The ratio of the length of the specimen to the diameter of the drunk body, L/D, is ≥ 3.
Experimental steps
To ensure measurement accuracy, the measuring instrument and the specimen should be conducted in the same environment. Potential contact spacing (AL); 1/L ≤ AL<3/LCL is the length of the sample.
Adjust the resistivity tester (Figure 3) so that the current intensity passing through the specimen is numerically equal to S/AL.
Clamp the specimen on the test bench, press the current button to allow the current to pass along the axis of the specimen's compression, and read the resistivity value.
During measurement, measuring current will increase the humidity of the sample. Therefore, it is required to keep the measurement time as short as possible (not exceeding 1 minute) and the current density below 1 A/srm2 to ensure that the change in resistivity caused by heating does not exceed ± 0.5%.
allowable error
The allowable error for measuring the resistivity of carbon materials is 2%,
The test report includes the following contents:; a) Entrusting unit; b) Sample number, name, and specifications; ）Single value and average value of test results, d) potential contact spacing; e) The current value during measurement;
g) Reviewers; h) Test date.