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John Ndanusa Akanya, Obiora Ferdinand Manafa
STANDARDIZATION – THE SON EXPERIENCE

Standards Organisation of Nigeria (SON) was established by Decree No. 56 of 1971 and statutorily charged with the responsibility for National Policy on Metrology, Standards, Testing and Quality Control (MSTQ) in Nigeria. Standardization activities carried out by SON range from development and approval of standards, quality assurance, inspection and testing, certification and calibration. Hardness measurement plays a vital role in Standardization. Product and System certification programmes of SON have recorded a considerable number of hardness measurements in industries, oil & gas facilities, laboratories and research institutions. This paper gives a detailed report of the Standardization activities in SON with emphases on Metrology. It started by giving a full description of the corporate entity, legal status, organizational structure, human and technical resources of SON. The paper goes further to show the functions and detailed activities of SON, including limits of capability. The role of hardness tests and values in quality assurance activities is given a considerable portion in this paper. The development of Metrological Infrastructure, which enhanced the promotion of Standardization activities in SON, is also highlighted. Fields of Measurements available in SON Metrology laboratory are enumerated. Institutional support and international co-operation with various foreign bodies and international organizations are included in the paper. In conclusion, the paper outlines the way forward to ensure the growth of metrology, hardness measurement in particular, and effective Standardization activities in SON.

G.W. Bahng, N.H. Tak, J.Y. Song and J.H. Hahn
TEST CYCLE CALIBRATION SYSTEM FOR ROCKWELL HARDNESS TESTER

The direct verification of Rockwell testing machines comprises four parts such as test force, indenter, depth measuring device, and testing cycle as seen in ISO 6508-2. Among them, the verification of testing cycle is generally carried out by using a stopwatch on industrial sites, which is not so reliable. In addition to this, most of commercial hardness testing machines produced nowadays are automatically controlled by the embedded software, which makes it much more difficult to calibrate the testing cycle. It implies that even though hardness testing machines are advanced more, the calibration of the testing cycle does not keep up with their advancement. To overcome this problem, an on-site calibration system was developed to calibrate the testing cycle of both the automatically controlled as well as manually controlled Rockwell hardness testing machines. The calibration system is composed of load cell, indentation depth measuring apparatus and embedded clock. Using this system, measurement of test force, application velocity of test force, and indentation depth are possible simultaneously in real time, which enhances the efficiency and reliability of calibration procedure.

Takashi Usuda, Hajime Ishida, Yutaka Seino, Satoshi Takagi, Koichiro Hattori, Hidetaka Imai
CALIBRATION AND MEASUREMENT CAPABILITY MONITORING PROCESS UNDER APMP ACTIVITIES

With reference to CIPM-MRA (Mutual recognition of national measurement standards and of calibration and measurement certificates issued by national metrology institutes), APMP (Asia Pacific Metrology Programme) have established 11 TCs (Technical Committees) including TCM (Technical Committee of Mass related quantities) which discusses hardness related issues in APMP. Under the TC activities, the guidelines and procedures for accepting CMCs (Calibration and Measurement Capabilities) and QS (Quality System) have been drawn up by taking closer cooperation with the JCRB (Joint Committee of the RMOs and the BIPM). Therefore, the concept of the procedures and guidelines are effectively introduced in the course of intra-regional and inter-regional reviews for submitted CMCs within APMP and from other RMOs (Regional Metrology Organizations), respectively.

Hiroshi Yamamoto , Takashi Yamamoto
DEVELOPMENT OF HIGH-ACCURACY HARDNESS STANDARD BLOCKS IN JAPAN AND FUTURE OUTLOOK

The sources of problems with a hardness testing machine that are detectable via day-to-day inspection using hardness standard blocks, or indirect verification, can be roughly divided into three: the indenter, the test force, and the indentation measuring apparatus. If any problems are detected, repair or recalibration of the testing machine, focusing on the aforementioned three factors, is carried out based on the results of verifying the direct accuracies of that machine. These efforts have been accumulated to acquire the high level of hardness testing technology as is available now. This article describes the development of a hardness standard block as a tool for indirect verification of hardness testing machines, discusses possible factors that have effects on hardness measurements, and provides insights into the future hardness tests from a perspective of a hardness block manufacturer.

Joachim Frühauf, Eva Gärtner, Konrad Herrmann, Febo Menelao, Dieter Schwenk, Thomas Chudoba, Hans-Peter Vollmar
CALIBRATION OF INSTRUMENTS FOR HARDNESS TESTING BY USE OF A STANDARD

As a standard for the calibration of force and depth scales of hardness testing instruments a system of silicon springs is described. The standard shows a linear force-deflection characteristic F = k · f up to a stop point (typical: Fst = 420 mN; fst = 22 µm). For the calibration of stiffness and stop point of the standard the characteristic should be measured using a spherical indenter. In view of the practical application for the assessment of instruments also Vickers indenters can be used. In this case indentations are produced. The resulting wear can be minimized by reducing the maximum force and using only the measured stiffness k for a quick assessment.

Satoshi Takagi, Christian Ullner
CRITICAL CHECK OF THE REPEATABLITY AND BIAS OF HARDNESS TESTING MACHINES RESTRICTED BY THE HARDNESS STANDARDS

Since the ISO standards for four major hardness scales were revised in 2005, the indirect verification has been considered as the mainstream of the traceability chain of hardness. In the recommended procedure of ISO, the uncertainty of hardness machine should be estimated and added to the combined uncertainty of hardness measurement value. The equation to calculate this uncertainty component was introduced according to the rectangular distribution of bias of hardness machines. However, if the error propagation is investigated in detail, the uncertainty of hardness machines should be obtained by considering the probability distributions of the uniformity of hardness reference block, the repeatability and the bias of hardness machine. In addition, the distribution of verification results should be calculated after some hardness machines are screened out by the maximum permissible values requested in ISO. In this paper, the probability distribution of the hardness machines, which passed in the indirect verification, are obtained by means of the Monte Carlo method. Since a calibration value of hardness is obtained only by measuring a specimen, it is not possible to separate the uncertainties of hardness machine and hardness block. Then the result of indirect verification is affected by the uniformity of reference block. The relation between the distribution of passed hardness machines and the uniformity of reference blocks is presented for several hardness scales. In addition, the guideline to estimate the uncertainty of the measured hardness values can be verified by means of the Monte Carlo method.

Masayuki Fujitsuka, Makoto Yamaguchi, Shigeru Ueno, Genichiro Kamiyama, Shigeo Katayama
MEASUREMENT OF A RESIDUAL IMPRESSION BY THE LASER SCANNING MICROSCOPE WITH DIC UNIT

When the nanoindentation testing is carried out, it is very important to understand the residual impression and the surface around it. Generally Atomic Force Microscopy (AFM) is used to obtain them. However, it is necessary to understand correct shape in the point of cantilever in AFM procedure. And, measuring them by AFM procedure precisely, very long measurement time and very clean environment and so on are needed. So, there are many difficulties to use AFM procedure for measuring residual impression and the surface around it. On the other hand, there are some procedures to measure them. Scanning Electro Microscopy (SEM) is effective to the grasp of the shape of the surface and the ruggedness. But, this procedure needs the coating of the sample and the vacuum atmosphere. Therefore it is not a simple and quick procedure. In this paper, authors used the laser scanning microscope with a differential interference contrast unit to obtain the data of a residual impression and the surface around it. This procedure is the very simple and quick procedure in no contact and measuring in various environmental conditions. The data of indentation depth from this procedure is obtained at the nano-meter order. The results from this procedure compare with the results from displacement of nanoindentation test.

Yutaka Seino
ANALYSIS OF INDENTATION DEPTH DEPENDENCE OF ELASTIC PROPERTIES OF INTER-LAYER DIELECTRIC FILMS ON SILICON

Analysis of indentation depth dependence of elastic modulus of soft films on silicon substrate measured by nanoindentation was studied. The experimental results were compared with two existing models that describe the effects of the substrate on elastic modulus of layered solid. Saha-Nix model that is the recent modification of King model agreed well with the experimental results to a certain limit of the indentation depth. It was found that the depth limit which Saha-Nix model is valid depended almost linearly on the relative elastic modulus of the film to the substrate Ef/Es. We further introduced an additional scaling parameter that is a linear function of Ef/Es in Saha-Nix model. The improved model was applied to porous silica low-k films. The model predicted a constant intrinsic elastic modulus of the film up to a depth of 30 % of the film thickness.

Shigeo Sato, Masayuki Sato
HARDNESS MEASUREMENT OF COATING THIN FILM BY INDENTATION PROFILE OBSERVATION USING SCANNING PROBE MICROSCOPY

According to the principle of a conventional Vickers (Berkovich) hardness measurement, hardness is calculated from diagonal lengths or side lengths of indentation. The diagonal length, the conjunction line length of pyramidal indentation, and the distance from the vertex to the base of trigonal pyramidal indentation are measured accurately by observing a vertical cross section. Scanning probe microscopy (SPM) is a good method for observing the vertical and horizontal cross sections of the indentation. However, such parameters in the cross section profile must be defined as the principle of the method to obtain a reliable nano-hardness value.

Vytautas Vasauskas, Juozas Padgurskas, Raimundas Rukuiza
THE MICRO-HARDNESS ANISOTROPY OF FLUOR-OLIGOMERIC AND Fe-Co-W COATINGS

The influences of indenter micro-geometry on the micro-hardness performance in the film/substrate system are discussed. Experimental results verify the force required to produce hardness indents for thin films, the measurement of the size of plastic zone cross-sections of the indents, and the characterisation of the indenters. It was found that the deformation is highly localised beneath the indenter and failures in the corners of pyramidal indenters occurred.

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