GB/T 39978-2021 English PDFUS$259.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email. GB/T 39978-2021: Nanotechnology - Resistivity of carbon nanotube powder - Four probe method Status: Valid
Basic dataStandard ID: GB/T 39978-2021 (GB/T39978-2021)Description (Translated English): Nanotechnology - Resistivity of carbon nanotube powder - Four probe method Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: G13 Word Count Estimation: 14,174 Issuing agency(ies): State Administration for Market Regulation, China National Standardization Administration GB/T 39978-2021: Nanotechnology - Resistivity of carbon nanotube powder - Four probe method---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.(Nanotechnology, carbon nanotube powder resistivity, four-probe method) ICS 59.100.20 G13 National Standards of People's Republic of China Nanotechnology Carbon Nanotube Powder Resistivity Four-Probe Method Fourprobemethod Released on 2021-05-21 2021-12-01 implementation State Administration of Market Supervision and Administration Issued by the National Standardization Management Committee Table of contentsForeword Ⅰ 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Principle 2 5 Instruments and test gauges 3 5.1 Balance 3 5.2 Powder tablet machine 3 5.3 Four-probe resistivity tester 3 5.4 Drying oven 3 5.5 Screw Micrometer 3 5.6 Reagent 3 6 Environmental requirements 3 7 Sampling and sample preparation 3 7.1 Sampling 3 7.2 Sample pretreatment 5 7.3 Sample preparation 5 8 Test Step 5 9 Result analysis 5 9.1 Test results 5 9.2 Analysis of sources of uncertainty 6 10 Test report 6 Appendix A (informative appendix) Case study 7 Appendix B (informative appendix) Test report 10 Nanotechnology Carbon Nanotube Powder Resistivity Four-Probe Method1 ScopeThis standard specifies a four-probe test method for the resistivity of carbon nanotube powder pressed into a thick block. This standard applies to the four-probe method to test the resistivity of carbon nanotube powder with a sample thickness greater than 4 times the probe pitch. other The powder resistivity test of carbon materials can be carried out by reference.2 Normative referencesThe following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document. GB/T 5314-2011 Powder sampling method for powder metallurgy GB/T 8170 Numerical rounding rules and the expression and determination of limit values JJG508 four-probe resistivity tester SJ/T 10315 General technical conditions for four-point probe3 Terms and definitionsThe following terms and definitions apply to this document. 3.1 Volume resistivity Under a given time and voltage, the ratio of the intensity of the DC electric field to the current density inside the material. Note 1.In practice, the volume resistivity is usually regarded as the volume resistance per unit volume. Note 2.The unit of volume resistivity is expressed in Ω·m. In fact, because the resistivity of carbon nanotube powder is small, mΩ·cm or Ω·cm can be used. Note 3.Rewrite GB/T 31838.2-2019, definition 3.2. 3.2 Powder resistivity powderresistivity The volume resistivity of the powder material. Note. The influencing factors mainly come from intrinsic resistance and contact resistance, ignoring barrier resistance. 3.3 Batch lot The quantity of powder produced or processed under the same conditions. [GB/T 5314-2011, definition 2.1] 3.4 Increment The powder obtained at one time from a batch of powder with a sampling device. [GB/T 5314-2011, definition 2.2] 3.5 Grosssample It is composed of all the sub-samples taken from a batch of powder, and the quantity of powder should be enough for the test. [GB/T 5314-2011, definition 2.3] 3.6 Compositesample The whole sample or part of it after thorough mixing. Note 1.You can choose to reduce the whole batch to obtain. Note 2.Rewrite GB/T 5314-2011, definition 2.4. 3.7 Testsample In order to determine a certain property or prepare a test piece, the powder removed from the mixed sample. Note. It is usually obtained from the mixed sample. [GB/T 5314-2011, definition 2.5]4 PrincipleFour equidistant probes are arranged vertically in a row (see Figure 1), and at the same time, apply appropriate pressure to press them on the surface of the sample to form an ohm. Contact, the distance between the sample and the probe can be ideally regarded as infinite, using a constant current source to pass a small current to the two outer probes 1 and 4, and the current value I is determined by the resistivity range value of the tested sample, and then use a high input impedance precision voltmeter to measure the electrical Pressure drop U. According to the theoretical formula (1) derived from the thick block principle and the thin layer principle, the resistivity of the sample can be calculated.5 Instruments and reagents5.1 Balance The accuracy of the photoelectric analytical balance or electronic balance should not be less than 0.1g. 5.2 Powder tablet machine The powder tablet machine should consist of the following two parts. a) Mold. The diameter of the cavity of the mold should not be less than 11 times the probe spacing, the allowable deviation should not be more than 0.02mm, and the height of the bulk powder should not be Less than four times the probe pitch; b) Tablet press. The piston diameter of the tablet press should not be less than the diameter of the die base, and it should be able to apply sufficient pressure with an accuracy of 1%. 5.3 Four-probe resistivity tester 5.3.1 The instrument is mainly composed of electrical part and probe part. The electrical part generally includes adjustable steady current source, A/D converter, digital display Instruments and components such as switches, reversing switches, etc. The probe part generally includes probe fixtures, probes and test benches, and the technical indicators of the probes should meet The provisions of SJ/T 10315. 5.3.2 The distance between the probes should be 1mm±0.01mm, the insulation resistance between the needles should not be less than 1000MΩ, and the mechanical migration rate should not be more than 0.3%. 5.3.3 The verification of the four-probe resistivity tester shall be carried out in accordance with the requirements in JJG508. 5.4 Drying oven The temperature can be controlled between 0°C and 300°C, and the temperature control accuracy is ±5°C. 5.5 Screw micrometer The accuracy should not be less than 0.01mm. 5.6 Reagents Anhydrous ethanol with a purity of more than 99%.6 Environmental requirementsThe temperature is 20℃±5℃, and the relative humidity should not exceed 65%.7 Sampling and sample preparation7.1 Sampling 7.1.1 General The mixed sample composed of the incremental samples should represent the batch of powder as accurately as possible. All surfaces of the sampler in contact with the powder should be smooth and clean. The properties of the powder should not be changed during the sampling process. Note. When a batch of powder is in motion, such as during loading, discharging, transportation and storage, the container will be shaken and uneven mixing may occur. 7.1.2 Number of incremental samples 7.1.2.1 Sampling during continuous discharge If the whole batch of powder is discharged continuously through an opening, sampling can be done at the time of discharging. At this time, during the entire discharge period, press Sampling at regular intervals. The number of increments depends on the required accuracy. At least three copies should be taken, one is taken after the discharge begins, and the other is taken after the discharge. Take it in the middle of the process, and take one part before the end of the discharge. 7.1.2.2 Sampling from the powder in the container Unless otherwise agreed, when sampling from a powder batch packed in a container, it should be randomly selected in accordance with the provisions of Table 1.Draw out of each container Take out one or more copies to form a total sample. If containers with different amounts of powder are included in a batch, the selected container should be The batch is representative, and the number of samples taken in each selected container should be proportional to the amount of powder in the container. Table 1 Selection table of the number of sampling containers 7.1.3 Sampling process 7.1.3.1 Sampling during continuous discharge The size of the sampling container in the direction perpendicular to the powder flow should be larger than the cross-sectional size of the powder flow by a sufficient margin. In case of sampling The powder spilled. When the sampling container is fed and withdrawn from the powder stream, the opportunities for each part of the powder to flow into the container should be equal. The total sample obtained should be Rotate at a speed of 15r/min~30r/min for 10 to 15 revolutions to obtain a mixed sample. Note. The simplest method is to make a sampler with a rectangular cross-section across the powder flow at constant velocity. 7.1.3.2 Sampling from the powder in the container Different types of samplers can be used to sample the powder contained in the container. The length of the sampler is so that the powder can be taken out from the various depths of the container. The end is appropriate. The total sample obtained should be rotated at a speed of 15r/min~30r/min for 10 to 15 revolutions to obtain a mixed sample. 7.1.3.3 Sampling the whole batch The reduced sampling of the whole batch of powder can be carried out in accordance with the provisions of 4.3 in GB/T 5314-2011. 7.2 Sample pretreatment Place the mixed sample in a drying oven at 105°C for 2h, and then transfer it to a desiccator for natural cooling. 7.3 Sample preparation 7.3.1 Clean the mold with dust-free paper or absorbent cotton dipped in an appropriate amount of absolute ethanol. 7.3.2 Weigh a mixed sample of a certain quality according to the selected mold size and transfer it to the mold to ensure that the mixed sample is evenly distributed in the mold. Pressure After completion, the thickness of the sample should be greater than four times the probe pitch. 7.3.3 Gently place the mold in the center of the tablet press, press the operating instructions of the tablet press, and increase the pressure to the set value (the set value is related to the sample type, push The recommended pressure is 10MPa~20MPa), keep it under this pressure for 0.5min~1min, then slowly release the pressure and take out the sample. 7.3.4 Observe and record the thickness of the sample. If the surface of the sample is flat, the thickness is uniform, and the distance between the probes is greater than four times, the resistance can be directly performed. Rate test, otherwise you need to re-sampling and pressing the tablet.8 test steps8.1 The four-probe resistivity tester will warm up for 30 minutes after it is turned on. 8.2 Open the four-probe test software, select the test type as "bar/thick block resistivity", evaluate the resistivity range according to the material, and select the appropriate For the current range, see Table 2. Table 2 Current range selection table of different resistivity samples 8.3 Place the sample prepared in 7.3 in the center of the test bench, and lower the probe to the center of the sample surface until the host has a current display. 8.4 According to the current value given on the test software, turn the adjustment knob on the device host to adjust the current so that it is the same as the current value displayed by the test software. The flow value is the same. Press the "Test" button to measure the resistivity value of the sample. 8.5 Change the test points by rotating the sample surface by about 30°~90°, repeat 8.3 and 8.4, and the number of tests n is not less than 5 times. Find sample n The average of the test results. If the relative standard deviation (Relative Standard Deviation, RSD) is greater than 5%, the test should be re-compressed. According to the requirements of GB/T 8170, the result is rounded to one decimal place. 8.6 After the test, wipe the probe clean with dust-free paper or absorbent cotton dipped in an appropriate amount of absolute ethanol.9 Result analysis9.1 Test results 9.1.1 The test result of sample resistivity can be obtained by formula (2). 9.2 Analysis of sources of uncertainty Uncertainty includes but is not limited to the following sources. a) The uncertainty introduced by the measurement accuracy of the instrument; b) Uncertainty introduced by measurement repeatability; c) The uncertainty introduced by the uniformity of the sample. 10 Test report The content of the report includes but is not limited to the following information. a) According to the standard number; b) Sample name; c) Laboratory personnel and test date; d) Test environment, including temperature and humidity; e) The instrument and model used for the test; f) Sample preparation conditions, including die diameter, sample amount, pressure size, pressure holding time, etc.; g) test results; h) Anomalies observed. Note. See Appendix B for an example of the test report.Appendix A(Informative appendix) Case Analysis A.1 Carbon nanotube samples Commercialized carbon nanotube samples. A.2 Instruments and reagents A.2.1 Balance Electronic balance with an accuracy of 0.1g. A.2.2 Powder tablet press Select the appropriate mold and tablet press according to 5.2.The diameter of the mold cavity selected in this example is 13mm, and the diameter of the base is 50mm. The pressure range of the tablet machine is 0MPa~40MPa, and the piston diameter is 90mm. A.2.3 Four-probe resistivity tester Choose a suitable four-probe resistivity tester according to 5.3, and the distance between the probes is 1mm±0.01mm. A.2.4 Drying oven Electric heating constant temperature blast drying oven. A.2.5 Screw micrometer The accuracy is 0.01mm. A.2.6 Anhydrous ethanol The purity is 99%. A.3 Test environment The temperature is 23℃ and the relative humidity is 60%. A.4 Sampling and sample preparation A.4.1 Sampling According to 7.1.2.2 and 7.1.3.2, use a sampler to randomly sample three incremental samples from a bag of carbon nanotube powder to form a total sample. The sample is rotated 15 times at a speed of 30r/min to obtain a mixed sample. A.4.2 Sample pretreatment Pre-treat the mixed sample according to 7.2. A.4.3 Sample preparation The sample preparation steps are as follows. a) Take out the mold and clean it with absorbent cotton dipped in an appropriate amount of absolute ethanol; b) Use an electronic balance to weigh 0.3g of the pretreated mixed sample and transfer it to the mold, and the mixed sample is evenly distributed in the mold; c) Perform tablet compression in accordance with 7.3.3, increase the pressure to 10 MPa, maintain the pressure for 0.5 min, then slowly release the pressure, and take out sample A; d) Observe and record the thickness of sample A in accordance with 7.3.4. A.5 Test procedure The test steps are as follows. a) The four-probe resistivity tester is turned on and preheated for 30 minutes before measuring; b) Open the four-probe test software, select the test type as "bar/thick block resistivity", modify the probe coefficient to 6.28, according to the material evaluation Estimate the resistivity range and select the current range as 100mA; c) Place the sample A prepared in A.4.3 at the center of the test bench, and lower the probe to the center of the surface of the sample A to The host has a current display; d) According to the current value given on the test software, turn the adjustment knob on the device host to adjust the current so that it matches the value displayed by the test software. The current values are the same. Press the "Test" button to measure the resistivity ρ1 of sample A; e) Change the test points by rotating the surface of sample A by 30°~90°, repeat the test steps of c) and d), and measure the resistivity of sample A ρ2, ρ3, ρ4, ρ5; f) After the test, wipe the probe clean with absorbent cotton dipped in an appropriate amount of absolute ethanol. A.6 Test results A.6.1 Table A.1 shows the measured resistivity value of sample A after tableting and sample preparation. The average electrical resistance of sample A is calculated according to formula (2). Resistance rate. ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 39978-2021_English be delivered?Answer: Upon your order, we will start to translate GB/T 39978-2021_English as soon as possible, and keep you informed of the progress. The lead time is typically 1 ~ 3 working days. 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