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This paper presents the results of a study on the development of alumina-based porosity reference materials (RMs), which are intended for controlling the accuracy of the measurement results obtained using the mercury porosimetry method. These mercury porosimetry RMs are being developed in the Russian Federation for the first time and are primarily intended for verification / calibration and testing for type approval of mercury porosimeters. The study of metrological characteristics was conducted using a reference system, which is to be included in the GET 210-2014 State Primary Measurement Standard for units of specific gas adsorption, specific surface area, specific volume and pore size of solid substances and materials. This reference system was calibrated prior to conducting the study with the use of external reference pressure sensors of the 2nd order at 0.6 MPa and 400 MPa, as well as a laboratory balance (special accuracy class 1) having a maximum weighing limit of220 g. In the course of conducted research work, procedures for reproducing and estimating the uncertainty of porosity characteristics using the mercury porosimetry method were developed. When estimating the PM metrological characteristics, the standard uncertainty, associated with the characterisation and heterogeneity of the studied materials (PM candidates), was evaluated. The standard uncertainty due to instability was disregarded due to the high stability of the alumina matrix. According to the results of the conducted studies, four types of alumina-based porosity PM were developed. Their pore sizes are of about -lOnm; -2,000 nm; -9,000 nm; -60,000 nm. The RMs with pore sizes of -10 nm; -2,000 nm were intended for use in controlling the accuracy of mercury porosimeters operating at high pressures, while the RMs with pore sizes of -9,000 nm; -60,000 nm were for controlling the accuracy of mercury porosimeters operating at low pressures. The developed RMs are different from their foreign counterparts, which are produced by BAM (Germany) and NIST (USA) metrological institutes. The standard uncertainty due to characterisation of the RMs in question was estimated, not by the method of interlaboratory experiment, but by a full analysis of the constraint equations taking into account all sources of uncertainty included in the equations on the basis of the Guide to the Expression of Uncertainty in Measurement. The conducted studies allowed the RM certified values to be traceable at this stage to the GET 3-2008 State Primary Measurement Standard for the mass unit (kilogram), the GET 101-2011 State Primary Measurement Standard for the pressure unit in the field of absolute pressure in the range 1×10–1– 7×105 Pa, the GET 43-2013 State Primary Measurement Standard for the pressure unit in the range 10-1600 MPa and the effective area of the piston-cylinder unit of dead weight testers in the range 0.05-1 cm2. In addition, a reference material having a large pore size of -60,000 nm, which currently has no analogues elsewhere in the world, was characterised.

Currently, in the Russian Federation, the metrological traceability of certified reference materials of the composition of gas mixtures in cylinders under pressure produced by manufacturers of certified reference materials is carried out in accordance with GOST 8.578-2014. Considering that certified reference materials of the composition of gas mixtures in cylinders under pressure are used for testing to approye the type of measuring instruments, verification, calibration, and graduation of gas-analytical measuring instruments used to control explosive gases and vapors, harmful components in the atmospheric air and the air of the working area, emissions from vehicles and enterprises, to control technological processes, the quality of hydrocarbon products, etc., the issue of ensuring the quality of seriously produced certified reference materials (about 100.000 cylinders with gas mixtures per year) is important. To ensure the quality of certified reference materials of gas mixtures in cylinders under pressure, mass-produced by manufacturers of certified reference materials, we offer the following actions:– manufacturers of certified reference materials’ passing of mandatory accreditation for compliance with the requirements of GOST ISO Guide 34–2014 and GOST ISO Guide 35–2015;– manufacturers of certified reference materials’ constant participation in the proficiency testing programs through interlaboratory tests;– actualizing and refining the existing set of standards defining the requirements for the entire life cycle of a certified reference material of a gas mixture in a cylinder under pressure;– improving the method of certification of a reference material by calculating the value of the expanded uncertainty of the reference material and the introducting a new coefficient «technological reserve».

Introduction The introduction indicates the need for the use of permanent magnets in various technology fields. The necessity of measuring the limit magnetic hysteresis loop for the correct calculation of magnetic system parameters is considered. The main sources of error when measuring boundary hysteresis loops are given. The practical impossibility of verifying blocks of magnetic measuring systems element-by-element is noted. This paper is devoted to the development of reference materials (RMs) for the magnetic properties of hard magnetic materials based on Nd2Fe14B, a highly anisotropic intermetallic compound.Materials and measuring methods Nd-Fe-B permanent magnets were selected as the material for developing the RMs. RM certified values were established using a CYCLE‑3 apparatus included in the GET 198‑2017 State Primary Measurement Standard for units of magnetic loss power, magnetic induction of constant magnetic field in a range from 0.1 to 2.5 T and magnetic flux in a range from 1·10–5 to 3·10–2 Wb.Results and its discussion Based on the experimentally obtained boundary hysteresis loops, the magnetic characteristics were evaluated, the interval of permitted certified values was set, the measurement result uncertainty of certified values was estimated, the RM validity period was established and the first RM batch was released.Conclusion On the basis of conducted studies, the RM type for magnetic properties of NdFeB alloy-based hard magnetic materials was approved (MS NdFeB set). The developed RM set was registered under the numbers GSO 11059–2018 / GSO 11062–2018 in the State RM Register of the Russian Federation.

The State Primary Measurement Standard for units of specific gas adsorption, specific surface area, specific volume and pore size of solid substances and materials (GET 210–2014) is currently in operation at UNIIM. The GET 210-2014 has calibration and measurement capabilities for pore size in a range from 2 to 100 nm, while in practice there is a need to control the pore size of solid substances and materials in a range from 100 to 10,000 nm. In order to enhance the calibration and measurement capabilities of the GET 210-2014, it was proposed to include two reference systems implementing the methods of mercury porometry and stationary filtration into the measurement standard. This work considers the state of the metrology of porometry and presents the first results of studies on the metrological characteristics of reference systems implementing the methods of mercury porometry and stationary filtration. Algorithms for calculating the uncertainty of quantities being reproduced via the methods of mercury porometry and stationary filtration and characterizing the porosity of solids have been developed and tested. The reliability of the developed algorithms is confirmed by: the results of participation in 4 international comparisons, the measurements of foreign-made reference materials, along with the results of participation in 6 rounds of interlaboratory comparisons. The measurement standard improvement will provide metrological support to measuring instruments and measurement procedures for sorption properties, porosity and gas permeability of solid substances and materials in various industrial sectors. Thus, the metrological independence of the Russian Federation will be ensured and import substitution of expensive foreign reference materials carried out.