Metallographic microscope testing cemented carbide porosity implementation standards
The implementation standard of metallographic microscope detection of cemented carbide porosity is GB/T 3489-2015 metallographic determination of cemented carbide porosity and non-alloyed carbon. The detection steps are as follows:
1. The maximum size of the pores on the grinding surface is defined as the size of the pores.
2. For pores less than or equal to 10um, observe the polished surface of the sample under magnification of 100 or 200 times for evaluation.
3. For pores larger than 10um and smaller than 25um, observe the polished surface of the sample under a metallographic microscope with a magnification of 100 times, and evaluate it.
4. If it is necessary to inspect pores larger than 25um, it should be inspected under a metallographic microscope with an appropriate magnification of less than or equal to 100 times.
5. If the porosity or non-combined carbon is unevenly distributed on the grinding surface of the metallographic sample for inspection, its position must be identified, such as: top, top, edge (shell) and center, etc.
There are relatively many detection methods for cuttings and core porosity. In mud logging, drilling-time logging, microscope inspection of cuttings, and nuclear magnetic resonance analysis can measure cuttings and core porosity. In well logging, neutron compensation, density compensation, and acoustic transit time logging are commonly used methods for measuring porosity. Some universities and scientific research institutions have also developed special equipment for measuring cuttings porosity. There are disadvantages such as unquantifiable and large errors in mud logging and microscope inspection of cuttings during drilling, and high cost and cumbersome operations in NMR analysis; logging is carried out after the wellbore is formed and the drilling tool is raised, and the measurement time Relatively lagging behind; the cost of equipment developed by universities and scientific research institutions is relatively high, and the structure is relatively complicated. The Russian rock cuttings and core density porosity measuring instrument has the advantages of simple operation, easy-to-understand principle, low cost, easy maintenance, wide applicability, and strong real-time performance. It is necessary as a supplement to the existing methods.
Soil Porosity Definition
The coarse and fine soil particles of various shapes in the soil are assembled and arranged into a solid phase skeleton. There are pores of different widths and shapes inside the skeleton, forming a complex pore system. The percentage of the total pore volume to the soil volume is called soil porosity.
Experimental steps
(1) Use a ring knife with a volume of Vt, use the matching handle of the ring knife, and a soil cutter for sampling, that is, the soil volume is Vt;
(2) Take out the soil sample and weigh the wet weight ms' of the soil sample with an electronic balance;
(3) Dry soil samples by means of heating and drying, alcohol burning, freeze drying, etc.;
(4) Calculate the moisture content of the soil sample: w=(ms'-ms)/ms×100%;
(5) Put the dried soil sample into a measuring cylinder filled with water, and measure the volume Vs of the dry soil sample by the principle of drainage method;
(6) Calculate soil bulk density D and density d from formulas (1) and (2);
(7) On the basis of soil bulk density and density calculation, calculate soil porosity by formula (3).
