Slovenian National Building and Civil Engineering InstituteDimi;eva 12, Ljubljanafax> +386 1 280 44 84, http>⁄⁄www.zag.si, E-mail> info@zag.si

sem-eds@zag.si

SCANNING ELECTRON MICROSCOPY –SCANNING ELECTRON MICROSCOPY –SCANNING ELECTRON MICROSCOPY –SCANNING ELECTRON MICROSCOPY –SCANNING ELECTRON MICROSCOPY –SCANNING ELECTRON MICROSCOPY –A VIEW INTO THE MICROCOSMOS OF MATERIALSA VIEW INTO THE MICROCOSMOS OF MATERIALSA VIEW INTO THE MICROCOSMOS OF MATERIALSA VIEW INTO THE MICROCOSMOS OF MATERIALSA VIEW INTO THE MICROCOSMOS OF MATERIALSA VIEW INTO THE MICROCOSMOS OF MATERIALS

Cement paste with an added plasticizerCrystals of Ca(OH)Crystals of Ca(OH)2 in a calcium-silicate-hydrate gel

Observation of hydration processesObservation of hydration processesObservation of hydration processes

Information about the microtexture and microcomposition of Information about the microtexture and microcomposition of Information about the microtexture and microcomposition of materials can help us, in all fields of research into materials, to materials can help us, in all fields of research into materials, to materials can help us, in all fields of research into materials, to materials can help us, in all fields of research into materials, to understand better and assess more accurately their macroscopic understand better and assess more accurately their macroscopic understand better and assess more accurately their macroscopic understand better and assess more accurately their macroscopic properties, and to explain and, in some cases, even predict their properties, and to explain and, in some cases, even predict their properties, and to explain and, in some cases, even predict their properties, and to explain and, in some cases, even predict their behaviour during different kinds of procbehaviour during different kinds of procbehaviour during different kinds of processes. On the basis of esses. On the basis of such knowledge it is possible to adjust the properties of materials such knowledge it is possible to adjust the properties of materials such knowledge it is possible to adjust the properties of materials in a controlled manner.The most effective method of investigating the microtextural and The most effective method of investigating the microtextural and The most effective method of investigating the microtextural and The most effective method of investigating the microtextural and The most effective method of investigating the microtextural and microcompositional propertiemicrocompositional propertiemicrocompositional properties of materials is SEM aterials is SEM - Scanning - Scanning - Scanning Electron Microscopy, equipped with EDS - Energy Dispersive X-Electron Microscopy, equipped with EDS - Energy Dispersive X-Electron Microscopy, equipped with EDS - Energy Dispersive X-Ray Spectroscopy. First, SEM is used to observe the surfaces of Ray Spectroscopy. First, SEM is used to observe the surfaces of Ray Spectroscopy. First, SEM is used to observe the surfaces of test specimens, with high-resolutest specimens, with high-resolutest specimens, with high-resolution imaging, and then an EDS spectrometer can be used to perform qualitative and quantitative spectrometer can be used to perform qualitative and quantitative elemental analyses of particular parts of the test specimen, elemental analyses of particular parts of the test specimen, elemental analyses of particular parts of the test specimen, including line scans and\or mapping analyses across selected including line scans and\or mapping analyses across selected including line scans and\or mapping analyses across selected surfaces of the specimen. The typical resolution of SEM devices is surfaces of the specimen. The typical resolution of SEM devices is

0.01 µm or less. In addition to traditional high-vacuum SEM, where 0.01 µm or less. In addition to traditional high-vacuum SEM, where 0.01 µm or less. In addition to traditional high-vacuum SEM, where 0.01 µm or less. In addition to traditional high-vacuum SEM, where 0.01 µm or less. In addition to traditional high-vacuum SEM, where images can only be generated under high vacuum conditions images can only be generated under high vacuum conditions images can only be generated under high vacuum conditions images can only be generated under high vacuum conditions (below 10(below 10-3 Pa), a more recently developed technique, low-vacuum Pa), a more recently developed technique, low-vacuum Pa), a more recently developed technique, low-vacuum SEM, has been developed, which can be used at higher pressures SEM, has been developed, which can be used at higher pressures SEM, has been developed, which can be used at higher pressures (1 - 130 Pa). It has several important advantages when compared (1 - 130 Pa). It has several important advantages when compared (1 - 130 Pa). It has several important advantages when compared (1 - 130 Pa). It has several important advantages when compared to traditional high-vacuum SEM, to traditional high-vacuum SEM, to traditional high-vacuum SEM, as follows> (a) the surfaces of the test specimens do not, as is the case of (a) the surfaces of the test specimens do not, as is the case of (a) the surfaces of the test specimens do not, as is the case of (a) the surfaces of the test specimens do not, as is the case of

high-vacuum SEM, have to be specially prepared by coating the high-vacuum SEM, have to be specially prepared by coating the high-vacuum SEM, have to be specially prepared by coating the surface with a conductive layer (this means that the specimen surface with a conductive layer (this means that the specimen surface with a conductive layer (this means that the specimen retains its pristine form, and can be used for furtheretains its pristine form, and can be used for furtheretains its pristine form, and can be used for further tests)<

(b) analysis is simpler and quicker than in the case of high-(b) analysis is simpler and quicker than in the case of high-(b) analysis is simpler and quicker than in the case of high-(b) analysis is simpler and quicker than in the case of high-vacuum SEM, and monitoring of time-dependent processes can vacuum SEM, and monitoring of time-dependent processes can vacuum SEM, and monitoring of time-dependent processes can vacuum SEM, and monitoring of time-dependent processes can vacuum SEM, and monitoring of time-dependent processes can be more easily performed<

(c) special test specimens can be tested, e.g. those containing (c) special test specimens can be tested, e.g. those containing (c) special test specimens can be tested, e.g. those containing large amounts of water such as gels, pigments, biological test large amounts of water such as gels, pigments, biological test large amounts of water such as gels, pigments, biological test specimens, fresh cement pastes, mortars and concretes.specimens, fresh cement pastes, mortars and concretes.

Contact persons>

• Laboratory for Mineral Binders and Mortars>Jerneja Strupi Šuput, tel.> + 386 (0)1 2804 501

• Laboratory for Stone and Aggregates>Dr Ana Mladenovic, tel.> + 386 (0)1 2804 394

• Laboratory for Concrete>Maja Simon, tel.> + 386 (0)1 2804 334

• Laboratory for Metals, Corrosion and Anti-Corrosion Protection>Dr Mirjam Leban, tel.> + 386 (0)1 2804 504

• Laboratory for Ceramics and Refractory Materials>Vilma Ducman, tel.> + 386 (0)1 2804 438

• Laboratory for Polymers>Dr Andrijana Sever Škapin, tel.> + 386 (0)1 2804 268

• Laboratory for Thermal Performance>Friderik Knez, tel.> + 386 (0)1 2804 361

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Needles of etringite - these needles occur in concrete, as a result of sulphate corrosion

Monitoring of destructive reactions in concrete

The occurrence of gel (the cracked area) as the result of alkali-silica reaction and of etringite (needle-like crystals) at the boundary between the aggregate grain (above) and the cement paste (below), with linear element analysis along the marked line

Ca

SiO

The identification of clinker minerals in historical mortars is an important criterion for determining their age

Biocorrosion and framboidal pyrite in calcareous' sandstone from Strtenica

Investigation of historical materials

Crystallization of calcium carbonate from a saturated solution of calcium hydroxide, after the slaking of pieces of lime

Al

Ca

Mg

S

Si

The top layers of the facade of the abbey at Sti;na using EDS mapping analysis of The top layers of the facade of the abbey at Sti;na using EDS mapping analysis of individual elements (S, C, Ca) — transformation of calcium carbonate into calcium sulphate

EDS spot and mapping analysis is used to investigate layers of paint and mortars, EDS spot and mapping analysis is used to investigate layers of paint and mortars, as well as for the identification of pigments

Investigation of corrosion products

Cl

Pb

Cu

Zn

Corrosion on a test specimen made of bronze, showing the boundary between two differently corroded areas, using linear element analysis along the marked linealong the marked line

Two enlarged crystals of PbCl2 which have occurred on the zinc corrosion products of a bronze test specimen

Pb CuZn Cl

Pb Si

Determination and analysis of the morphological characteristics of materials

Al

Crystals of PbCl2 on zinc corrosion products, showing the EDS spectrum of the whole surface and the results of mapping analysis for individual elements (Pb, Zn, Cl and Cu) across the whole surface of the test specimen

Measuring of the thickness of different layers

The glaze on a ceramic tile

A reflective layer on glass

Amphibole asbestos

An inclusion in a glass product, observed using EDS “mapping” analysis of individual elements (Al, Pb and Si) across the selected surface of the test specimen

Published by ZAG Ljubljana • Photography by Matja/ Zupanc • English Translation by Peter Sheppard • Preparation and printing by Studio Graffit d.o.o., Ljubljana • April 2008

Technical specification of the model 5500 LV JEOL low-vacuum scanning electron microscope, with EDS analyser>

• high-vacuum mode + medium-to-low vacuum mode microscopy, in which the pressure can be varied over the range between 1 Pa and 130 Pa,

• accelerating voltage of between 0.5 and 30 kV,

• magnification of between 18 x and 300.000 x,

• resolution of 3.5 nm in the high-vacuum mode, and 5 nm in the medium-to-low vacuum mode,

• Secondary Electron Image (SEI) and Back-scattered Electron Image (BEI),

• test chamber of larger dimensions, made to order> maximum dimension (diameter) of the test specimen> approx. 16 cm,

• table movement> X = 80 mm, Y = 40 mm, Z = 43 mm, R = 360°, inclination range> -10° do 90°,

• a tungsten cathode,

• digital image processing,

• qualitative and semi-quantitative element analysis from B (boron) to U (uranium),

• mapping and linear analysis

Mineral fibres> (a) before ageing (b) after exposure to saturated humidity for a period of 3 years

(a)

(b)

Monitoring of time-dependent processes

Nanoparticles of anatase in a coating after chemical etching of the surface

Observation of nano materials