Reference materials for materials science

Reference materials for materials science

Maintaining and enhancing competitiveness of European companies is a prerequisite for increasing the level of employment in the European Union and to ensure sustained wealth of its citizens. The Europe 2020 strategy recognises this need and proposes measures that build upon the '1992 Programme' launched by the Single European Act of 1986. The Flagship Strategy "Resource efficient Europe" extends this focus on competition by the dimension of resource efficiency, based on less raw-material intensive design of products and the use of recycled material. Better product design critically relies on reliable knowledge of material properties, as only this allows reduction of unnecessary slack. This precise knowledge is achieved by standardised measurements of high accuracy, as demonstrated by e.g. Directive 97/23/EC (pressure equipment) and Directive 89/106/EC (construction materials), which prescribe the use of standardised tests (e.g. ISO-148, EN10045) to ensure the quality of raw materials (steel etc.) while maintaining competition within the European Union. These standards, and hence implementation of this legislation, prescribe the use of certified reference materials.

Moreover, the rapid economic development of, inter alia, India and China resulted in bottlenecks in the markets for raw materials. For this reason, the Flagship Strategy "An industrial policy for the globalisation era" calls for measures to tackle the challenge in commodity markets and to promote liberalisation of trade to create a level playing field for industry on a global scale. One important prerequisite for liberalised trade and free markets is comparability of measurements, as this ensures that specifications can be compared globally. This comparability of measurements is underpinned by certified reference materials. The JRC supports these initiatives by providing certified reference materials for the testing of fossil fuels, to allow laboratories within the Union and also worldwide, ensuring correctness of their measurements and effective control of specifications.

The JRC produces a wide range of materials; an exhaustive list can be retrieved via the online catalogue for reference materials. Recent activities include certified reference materials for mechanical properties of metals, morphological properties of particles and composition of plastics.

Certified reference materials for testing the mechanical properties of metals

Set of five samples broken in the Charpy test

The collapse of the Tuo river bridge (China) in 2007, killing 34 and injuring 22 and believed to be caused by poor quality materials illustrates the importance of building materials of sufficient quality. The impact toughness of steel is the energy that is needed to break a steel sample of a given dimensions. The standard ISO-148 ("Charpy test") describes how a specified sample is broken by a hammer and how the required energy is measured. This measurement is important for deciding whether a certain steel is fit for purpose. Therefore, European legislation for e.g. pressure equipment and construction materials prescribe this test and companies compete on a global scale offering steels with a given impact toughness. Proper execution of the test also includes regular checking with certified reference materials whether the testing equipment is functioning well. The JRC produces such reference materials under its scope of accreditation.. In this way, it contributes to a functioning measurement system that ensures quality of raw materials for buildings and industrial equipment. The JRC complements this work on reference materials by engaging in the preparation and revision of documentary standards: it is participating in the ISO technical committee on mechanical testing of material (ISO/TC164), which, amongst others, developed ISO-148.

Whereas impact toughness measures the resistance of steel to a sudden impact, many materials are subject to creep, i.e. slow deformation which is invisible by the naked eye. Also tests for creep are standardised and the JRC produced certified materials for demonstrating proper functioning of equipment.

Composition of metals

The impurities of alloys and pure metals often determine the price on the world market and accurate measurements are therefore crucial to ensure competition and access to world markets. To meet this demand, the JRC offers various alloys and pure metals (Cu, Ti, Pb, Zn, Zn alloys) certified for the mass fraction of various impurities. While development of some of these materials was funded by different European Commission initiatives in the past, the JRC had taken over sole responsibility for quality control of the finished materials and replacement of exhausted materials.

Morphological properties of particles

Particle size, surface area and pore-size volume are important parameters for many industrial processes. For example, concrete requires the components to have a clearly defined particle size. In addition, many industrial processes require transport of materials in a granular form, which also requires constant particle sizes.

The JRC supports quality control and technical development in this field by offering CRMs for particle size distributions and shear testing of particles between 350 nm to 5 mm size, pore size volume and specific surface area. This reference material work is complemented by intensive involvement in the development of documentary standards: IRMM is a liaison to the ISO Committee on particle characterisation excluding sieving (ISO/TC24/SC4) .

Composition of polymers

Certified reference materials for polybrominated flame retardants in polymers

European Legislation limits the mass fractions of elements and polybrominated flame retardants in electrical and electronic equipment (Directive 2002/95/EC), end of life vehicles (Directive 2000/53/EC) and on packaging and packaging waste (1994/62/EC). The importance of such regulation became clear when the Netherlands seized 1.3 million game consoles destined for the Christmas season because one cable contained too much cadmium. Reliable methods and common measurement standards are necessary for the industry to ensure that their supplies are in compliance with legislation as well as for regulators to ensure that no illegal material enters the European market.

The JRC is supporting laboratories in this field by developing certified reference materials for elements in plastics. The first material was released in 2000 and a second batch was released in 2007. In addition, the JRC released the world's first certified reference material for several flame retardants in plastics in 2008.