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GAL-VISION REFERENCE METROLOGICAL SYSTEM FOR THE MEASUREMENT OF VICKERS AND BRINELL INDENTATIONS
Produced by
LTF
A division of SpA Via Cremona 10 - 24051 Antegnate (BG) - ITALY Tel. +39 363 94901 (15 linee R.A.) Fax +39 363 914770 E-Mail: [email protected]
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CONTENTS 1.
DOCUMENT SUBJECT ................................................................................................. Page 3
2.
REFERENCE STANDARDS ........................................................................................ Page 3
3.
EQUIPMENT DESCRIPTION ....................................................................................... Page 4
4.
5.
3.1
Introduction ................................................................................................... Page 4
3.2
Functional features ....................................................................................... Page 5
3.3
Composition ................................................................................................. Page 7 3.3.1
Measurement station ....................................................................... Page 7
3.3.2
Control and processing unit ............................................................. Page 8
3.4
Connection to peripherals ........................................................................... Page 9
3.5
Environmental operating conditions ...................................................... Page 10
EQUIPMENT OPERATING FUNCTIONS ................................................................. Page 10 4.1
Sequential tests ........................................................................................ Page 11
4.2
Knoop indentations ................................................................................... Page 12
4.3
Self-control methodology .......................................................................... Page 12
REFERENCES AND PERFORMANCES ................................................................. Page 13 5.1
References ................................................................................................... Page 13
5.2
Performances and metrological comparisons ........................................ Page 16
5.3
Training, installation and commissioning of the system ....................... Page 16
6.
SUPPLIES .................................................................................................................... Page 17
7.
PARTS NOT INCLUDED IN THE SUPPLY .............................................................. Page 17
8
BIBLIOGRAPHY .......................................................................................................... Page 18
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GAL – VISION THE REFERENCE METROLOGICAL SYSTEM FOR THE MEASUREMENT OF VICKERS AND BRINELL INDENTATIONS
1.
DOCUMENT SUBJECT
This document describes the main technical features of the LTF System for Vickers and Brinell measurements, generated by LTF Standardizing Machine or by other conformed Hardness Testers Machine aimed at Primary and Secondary Laboratories, according to the relevant ISO Standards. In particular, the document describes the following information about the aforementioned equipment: functional features; general technical specifications; acquired references; Metrological performances. This equipment can be also considered as a Primary Device usable with the Hardness Standardization Machine too. 2.
REFERENCE STANDARDS For Vickers hardness tests:
a. b. c.
ISO 6507-1:2018, Metallic materials – Vickers hardness test - Part 1: Test method ISO 6507-2:2018, Metallic materials – Vickers hardness test – Part 2: Verification of testing machines ISO 6507-3:2018, Metallic materials – Vickers hardness test – Part 3: Calibration of reference blocks
For Brinell hardness tests: a. b.
c.
ISO 6506-1:2014, Metallic materials – Brinell hardness test - Part 1: Test method ISO 6506-2:2017, Metallic materials – Brinell hardness test - Part 2: Verification and calibration of testing machines ISO 6506-3:2014, Metallic materials – Brinell hardness test - Part 3: Calibration of reference blocks
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EQUIPMENT DESCRIPTION
3.1
Introduction
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Practical experience has shown that there are several sources of uncertainty, which affect the results of a Vickers and Brinell hardness test. In particular, the subjectivity of the indentation diagonal or diameter measurement is the determining part of the uncertainty and thus requires a special approach. In the past, numerous research studies were carried out /1,2/ to quantify the uncertainty in measuring the dimensions of a Vickers indentation: the results demonstrated that it is not possible to make a complete and significant evaluation of the effects of human factors such as concentration, fatigue, capacity to estimate the collimation conditions, etc. in order to take them into account in some way and eventually correct them. The only reasonable solution is to eliminate these influences by not allowing the operator to carry out this unproductive task and providing him with an automatic image processing System that can objectively measure the hardness indentations. In 1984, Barbato and Grattoni of the Istituto di Metrologia “G. Colonnetti” (IMGC) of the C.N.R. (National Research Council) patented (Patent no. 67181 - A/84) a computerized System that automatically measures the Vickers hardness, based on applying to the image the image processing algorithm indentations. This System eliminates any and all subjectivity by the operator when measuring the indentation, and thus attains a precision level that complies with the ISO Standard requirements. LTF acquired the exclusive license from C.N.R. to exploit this patent, based on which it has developed an entire family of computerized hardness and microhardness systems. In particular, one version is specifically designed for use as a metrological reference. Further, LTF in cooperation with IMGC modified that version in order to carry out Brinell indentation measurements by automatic procedure. The features and performances of this version are described in the following paragraphs.
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Functional features
The described System allows the measurement of Vickers or Brinell indentations generated on reference test blocks by LTF HSM Hardness Standarisation Machine or different device, according to the ISO 6507-3 and ISO 6506-3 Standards in terms of precision, accuracy and uncertainty. In particular, the System can: measure the diagonals of Vickers indentations according to ISO Standards, the diagonal must be more than 0.02 mm length; measure the diameters of Brinell indentations generated with hardmetal ball indenters (diameter of 1-2,5-5-10 mm).
Fig. 1 – A Gal-Vision overview
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As described at point 3.1 of this Technical Report, on the base of effective sizes of each indentation and to get the best accuracy, the System can carry out the aforementioned measurements by two different methods:
Indirect method: when the size of the indentation is less of the visual field captured by the camera, the System generally works with the indirect method; the System automatically looks for the indentation in the visual field and its diagonal or diameter measurement, and calculates the corresponding hardness value; the user can arrange himself the sizes of the research screen in the visual field for each measurement. Several software regulations can be to allow in order to get the best conditions of the readout. With the indirect method, the system is able to measure Vickers (and Brinell) indentations with diagonal (or diameter) lengths starting from 0.02 mm (using the proper lens) on the screen of the computer.
Direct method: when the size of the indentation is larger of the visual field due to choose lens, the System works with a Direct method (reading by probe & camera). The system moves automatically the left vertex, or point to be measured, in the middle of visual field; as in the other method, the dimension of the research screen can be varying; at this point, the System acquires coordinates of the probe for that position and stores it; in the same times, it carries out automatically the measurement of exact position of the vertex, or the point to be measured, from the center of the visual field; then, by using the motorized stage along the X direction (the same of the probe running) the right opposite vertex, or point to be measured, is automatically brought in the research screen and the System repeats again the aforementioned operations. At this point the User manually turns the indentation of 90° by a rotary stage and he manually aligns the second diagonal or diameter to be measured; now, all the operations, described on the aforementioned part, are carried out in the identical way in order to measure the second diagonal or diameter. At this point, the System automatically
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calculates the value of the diagonal or the diameter, by the two positions of the vertex respect to the centre of the visual field and the difference of the two coordinates of the probe. The maximum stroke of the probe is 12 mm, so that it is possible to carry out even measurements on large Brinell indentations, without any problem. A virtual Joystick is available in order to allow the User can move the test block along the xaxis without any software commands too. With the Direct method, the system is able to measure Brinell indentations realized in all scales; with ball indenters with 1-2-2,5-5-10 mm diameter, and Vickers indentations up to HV100 which may not be measured in the indirect method. For both aforementioned methods, the accuracy are according to the relevant ISO part 3, and guaranteed by calibrated stage micrometers. On request, a special version can be assembled using a laser head instead of the probe, in order to obtain more accuracy and performances. Of course with the direct method it is possible to find all the indentations measurable with the indirect method. 3.3
Composition The System consists of two main units, which are strictly interrelated: a measurement station a control and processing unit
3.3.1 Measurement station It consists essentially of:
a metallographic microscope, equipped with: LED illuminator, with a fine adjustment of framed field luminous intensity; 5-position objective holder including flat-achromatic objectives, 5X, 10X, (used for the positioning and the general view of the indentations; 20X, 50X e 100X used for the measurement USB 3.0 camera CMOS global shutter 1936x1216 gray, 1/1.2", 41 full frames/s, IR cut filter, C mount (or updated version); a multi cross-stage sample holder, with a configuration, as follows: First of all, as basis, a special stage for allowing manual movements till to16 mm along the z axis in order to keep the plane with the examined indentation on the focus plane containing the optical path of the microscope and the axis of the probe. Practically, the User makes the right focus by this stage and not by the microscope course focusing knob that is blocked a
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A 25 mm travel motorized x-axis commanded by the software or by virtual Joystick. A rotary table with two mechanical stops to allow to turn on 90° the indentation; the position of the mechanical stops can be registered fine in order to turn on the indentation with a good precision. A x - y manual motion by micrometric screw (3 mm travel) in order to center the indentation in the field of view manually. A circular plate for support of samples to be measured.
Fig. 2a – The multi cross tables with Heidenhain version
Fig. 2b – The multi cross tables with Laser Head version
A high accuracy linear transducer, 25 mm working stroke (12 mm travel) computer interfacing. The linear transducer is mounted upon a support in front to multi cross tables, perfectly aligned along x-axis motorized and focusing plane in order to minimize any errors (Abbe error). On request as optional, a special version can be available with a laser head (Fig. 2b) instead of the linear transducer (Fig 2a) for measuring with the best performances.
3.3.2 Control and processing unit This unit, located next to the measurement station, is responsible for controlling and driving the measurement cycle, data acquisition and processing, display, printing and filing of test results, as well as any interfacing with a laboratory management information System. The control and processing unit consists of:
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personal computer, actual configuration (or updated version): Gigabyte H110M-S2H Skt.1151 • INTEL SKYLAKE i7-7700 • Ram DDR4 8Gb 2133 PC4-17000 Kingston • Hard Disk 1Tb 3,5" 7.2K 64MB Seagate • Card Reader • DVD LG SATA 24X Nero Dual Layer • Case Cooler Master Elite 342 Windows W10 operating System; Microsoft Office (English language). LED flat monitor an ergonomic cabinet (optional) supports the microscope, the keyboard and the monitor upon a large flat with all the other components positioned inside. A useful chest of drawers allows to keep accessories too.
Fig. 3 – Vickers and Brinell automatic measures by Software
System control and processing software. the software utilizes one dedicated algorithm, thus ensuring an objective and reliable measurement of the indentations: based on the information contained in the image acquired from the camera, the positions are determined of the vertices of the indentation and thus the length of the two diagonals. The operator interfacing based on a window menu, is extremely easy to use and does not require any programming knowledge. Archive management,
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integrated in the program, is designed for a local network connection and for access to data by data base management software. Special calibrated stage micrometer, in order to allow the verification of measurement devices, including routines to calibrate the entire measurement System, thus guaranteeing the traceability of the system to length references. The Calibration Certificate will be issue by an accredited laboratory whose measurements are traceable to an European national length measurement standard. 3.4
Connection to peripherals As already mentioned, the system is designed for connection to peripheral units.
3.5
Environmental operating conditions
The System is designed for use in a laboratory environment, with the following limits for environmental conditions: temperature: 21 ± 2 °C relative humidity: 30 - 70%, without condensation. 4.
EQUIPMENT OPERATING FUNCTIONS
As already mentioned, the System is controlled by a Personal Computer which, through an easy-to-understand operator interfacing, displays the possible options each time along with a guide for selecting them. Therefore, when the System is turned on, it displays the menu of the possible operating phases. A summary of these phases is presented below.
Parameter Change: used to set the test parameters (load, dwell time, objective, number of tests, etc.) and of some personal data (operator, block serial number, archive file, etc.); Indentation Position: used to observe the visual field of the indentation and the block test surface, luminosity control, contrast and focusing; Indentation Measure: used to measure the indentation based on different operating procedures: direct method and Direct method as described in previous paragraphs. Archives: used to record on the disk and call files containing test parameters and/or the results of the tests performed; it is also possible to store and recall on the disk
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the images acquired from the camera for reporting purposes; further, it is possible to export the results directly into Word package by customized template.
4.1
Calibration: used to verify or, if requested, repeat the measurement System calibration, for the various objectives, with reference to an optional stage micrometer calibrated against a length sample. See fig. 4 showed below.
Sequential tests
The block calibration process consists of a series of hardness tests performed on the block to be calibrated by the Standardizing Machine, the measurement of the diagonals or diameters and calculation of the corresponding hardness and an evaluation of the relative uniformity based on the variation of the results obtained. After the indentation process, once the operator has selected the test parameters (load, number of tests, dwell-time), the System is used to observe the test surface of the block to ensure proper focusing and to choose the position on which to make the measurements. Once this choice has been made, the operator observes the indentation generated and makes the System measures it, using the direct or Direct method, described in the previous paragraphs. When the combine method is used, the System calculates only one diameter or diagonal, in the direction of the X axis. In order to carry out the measurement for the second orthogonal length, a semi-automatic apparatus allows to turn round the block and repeat the same procedure. After this cycle is repeated for the number of indentations required by the calibration cycle (5 according to ISO Standards), the System displays the following results: list of measurements performed (diagonals and hardness); average value of the vertical and horizontal diagonals and average diagonals;
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nominal hardness resulting from the calibration (arithmetic mean of the measured hardness values); uniformity of the block (spread of measurements); The results of the calibration operation can be saved on a disk or exported automatically in a Word template (for subsequent reading or to process succeeding statistical analyses using a suitable data management software package). It is also possible to print a calibration Report for each block that contains the block identification data and the calibration results. This type of operating procedure is particularly suitable for research activities or when setting up the calibration procedures and in any case in all those situations in which interaction is required between the operator and the System, to enhance operating flexibility. 4.2
Knoop indentations
With a modification to the software package, the System can also measure Knoop indentations. The same operating procedures described above for the Vickers tests are also valid for the Knoop tests. Since no metrological reference is currently available in Italy for the Knoop tests, given the minimum industrial diffusion with respect to the Vickers tests, it was not possible to carry out exhaustive metrological comparisons to determine the traceability of the System for such a test. 4.3
Self-control methodology
As required by ISO Standards, the System has been designed to be checked with a direct method. In particular, the measurement devise can be easily checked using the calibration software (included in the System) with reference to a special stage micrometer calibrated against a length reference, with a Calibration Certificate issue by an accredited laboratory whose measurements are traceable to an European national length measurement standard, as INRIM, the Italian National Primary Metrological Institute in Turin.
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REFERENCES AND PERFORMANCES
LTF-GALILEO REFERENCES Equipment for Primary Hardness HSM Hardness Standardization Machine (Rockwell, Brinell and Vickers) GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
NAME
TYPE OF EQUIPMENT
YEAR
NIST WASHINGTON, USA
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers)
1992
I.N.Ri.M. – Turin - Italy ( Former IMGC METROLOGY INSTITUTE G. COLONNETTI)
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers)
2000
NPL LONDON – U.K.
GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2000
INMETRO Rio De Janeiro Brazil
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations and GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
LTF S.p.A. ACCREDIA CALIBRATION CENTER ANTEGNATE, ITALY
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations and GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2005
HSM Hardness standardization Machine (Rockwell N/T scales) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations
2006
CFCU SOFIA- BULGARIA
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NAME NIM - CHINA NATIONAL METROLOGY INSTUTUTE – BEIJING, CHINA
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TYPE OF EQUIPMENT HSM Hardness standardization Machine – Lever Type and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations
12
YEAR
2006
GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations and GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2006
NPL NEW DELHI – INDIA
HSM Hardness standardization Machine (Rockwell N/T scales and Vickers/Brinell up to 100 kgf) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations
2007
NIST WASHINGTON, USA
GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations and GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2008
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers)
2009
GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2009
HEILONGJIANG ANHUA MEASURE CENTER – HARBIN, CHINA
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations
2010
KRISS KOREA RESEARCH INSTITUTE OF STANDARD & SCIENCE DAEJON – Republic of Korea
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations
2011
TUBITAK UME GEBZE/KOKAELI – TURKEY
DRML TIMISOARA, ROMANIA VNIIFTRI National Metrological Institute of Russia - MOSCOW
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YEAR
VNIIFTRI National Metrological Institute of Russia - MOSCOW
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers)
2015
SASO Riyadh - Saudi Arabia
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers) and GAL-VISION Reference Metrological System for measuring Vickers and Brinell indentations and GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2016
GAL-INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2017
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers)
2017
GAL INDENT Reference Metrological System for diamond Rockwell and Vickers indenters
2018
HSM Hardness standardization Machine (Rockwell, Brinell and Vickers)
2018
NIM - CHINA NATIONAL METROLOGY INSTUTUTE – BEIJING, CHINA
NIST WASHINGTON, USA
BEIJING METROLGICAL INSTITUTE 304, CHINA
BELGIM PRIMARY INSTITUTE, BELARUS
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Performances and metrological comparisons
Gal-Vision works as an indentation measuring system at high performances and it complies with ISO 6507 – 3 and ISO 6506 – 3 Standards requirements in terms of precision, accuracy and uncertainty. The system complies with requirements of the tender. Since the System adopted first by Officine Galileo up to 1994 and from then up to now by LTF is a first line reference of the ACCREDIA Laboratory, it is constantly monitored by the INRIM through audits. During use as a calibration reference the System has demonstrated, already from the very beginning, excellent agreement with the scale maintained at INRIM. In the bibliography, there are illustrated the results of the comparison between the Calibration Laboratory equipment and the INRIM primary reference: as can be easily seen, there is absolute agreement with the ISO Standard requirements. In addition, the objectivity of the measurement guarantees that the agreement is stable over time: in effect, over the last few years of activity, the calibration System being used at the ACCREDIA Laboratory has required re-calibration only during the transfer from Officine Galileo to LTF, thus proving the intrinsic stability of the System. Gal-Vision is a formidable tool for a Primary laboratory in the field of Hardness Calibration and Testing, even for the possibility of using the combine method that allows to measure either very large indentations and to increase the accuracy of the measurement using lenses with higher magnification. Finally, the fact that the uncertainty of the combine method is, in per cent, less than the one performed by direct method, is a further significant skill that let Gal-Vision unique in the world. 5.3
Training, installation and commissioning of the system
The installation and commissioning of the system with training of Customer laboratory staff (two persons) will be performed through the following stages: a) As optional, a metrological characterization using three Vickers indentations and three Brinell indentations, one master Vickers image and one master Brinell image, to be carry out upon the system c/o LTF by INRIM, formerly Metrological Institute G. Colonnetti, Turin, Italy (IMGC) that will produce a Technical Report; b) transport of the system to the installation at Customer’s site as/if defined in the offer; c) as/if defined in the offer, installation and commissioning of the system c/o Customer’s laboratory with training for two of Customer’s technicians on site by LTF’s technicians for a total duration of four days;
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Operation Manual and Technical Manual, with the roughly mechanical and electrical schemes of the machine, will be available in English language. 6.
SUPPLIES
The System has an electric power supply with a single-phase voltage rating of 110220V at 50-60 Hz. The System is equipped with a 2 pole + ground power supply cable with a socket that complies with CEE 17 (other solutions on request).
7.
PARTS NOT INCLUDED IN THE SUPPLY
Unless specifically indicated in the offer, the standard supply does not include the following parts and/or services: a. b. c. d. e. f. g. h. i. j. k.
characterization of the system by INRIM institute; installation, commissioning and training of the system c/o Customer’s laboratory; hardware and software connection to any laboratory local information network; additional lens (100x); special stage for z axis 55 mm travel; laser head instead of probe trasducer; ergonomic cabinet accident-prevention devices and protection units (if required); any software personalization (e.g. modification of printing formats, language change, etc.); software source lists; software for Knoop measurements.
LTF may be requested for any changes with respect to what is described in this Technical Report. LTF reserves the right to review and evaluate such changes from technical point of view.
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BIBLIOGRAPHY
1. HIDA, N. , YAMAMOTO, K.: “On the determination of absolute value of diagonal length of Vickers indentations”, Bulletin of the National Research Laboratory of Metrology, Tokyo, no. 4 18-25 2. BARBATO, G., DESOGUS, S.: “Problems in the measurement of Vickers and Brinell indentations”, Measurement, Vol. 4 No. 4 Oct-Dec, 1986, 137-147. 3. BARBATO, G. , CHIOSTRI, A., GORI, G., LIVI, S.: “ISOSCAN: a modular solution for Vickers and Knoop microhardness testing”, VDI-Berichte No. 804, 1990, 111-128. 4. BARBATO, G., DESOGUS, S, GRATTONI, P.: ”Automatic Vickers indentation measurement”. Document prepared for the XI Congress IMEKO, Houston (USA), 1988 5. BARBATO, G., GORI, G.: "Metrological references in Hardness Measurement: a necessary background for industrial Quality Assurance", Proceedings of the 5th Congreso Nacional de Metrologia Industrial, Zaragoza, 13-15 November 1991. 6. STANBURY, G.C., DAVIS F.A.: “Provision of hardness standards - Final report”, NPL REPORT CMAM 53, April 2000. 7. STANBURY, G.C., DAVIS F.A.: “Uk’s provision of Primary Hardness Standards”, proceedings of XVI IMEKO World Congress, Hofburg, Vienna, Austria, September 2528, 2000, Editors: M.N. Durakbasa, A. Afjehi-Sadat, P.H. Osanna. 8. LIGUORI, A., TUROTTI, F., GORI, G.: “LTF Spa Contribution to the Standardization of Hardness Measurements”, proceeding of XIV IMEKO World Congress, Beijing, China, 1998.
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