This paper presents equipment for the measurement of initial as well as final setting times of calcium phosphate cements containing alkali to achieve higher solubility. Until now, the selfsetting process of cements also if alkali is integrated has been tested by using the “standard test method for time of setting of hydraulic-cement paste by Gillmore needles” in accordance to ASTM C 266 – 99. This procedure needs high man power and, furthermore, the results have been markedly influenced by individual experiences that are incorporated in the criterion “without appreciable indentation”.

This article gives an overview of the development of the international standardization work for "Instrumented indentation testing" ISO 14577. The historical development and the main topics of this new international standard are described and discussed.

Material test results may depend strongly on the dynamic properties of the used testing machines. Unique methods and parameters for characterisation and validation of force or displacement controlled testing machines are still missing. In the presented paper a study of the control behaviour of a spindle driven uniaxial machine is carried out using a piezoelectric translator for generating the disturbance variable. The typical responses of the systematically optimized machine are compared to simulations of simplified controller systems. Some parameters concerning the time behaviour are discussed in terms of a systematic characterisation of the machine's dynamic properties and the experimental set up used.

The ISO/DIS 14577 Metallic materials - Instrumented indentation test for hardness and materials parameters - Part 1-3 (IIT) concerns test forces up to 30 kN. The paper reports on IIT at test forces ranging from 0.002 N to 1000 N on non - magnetizable steel X8 CrMnN 18-18 (1.386) with well polished surface using Vickers indenter and four hardness machines of different design (Nano Indenter XP, Fischerscope H 100, Zwick Z005 with Universal hardness head and a laboratory four-column set up materials testing machine) according to the standard. Using mostly identical test parameters the results of the different machines are almost in good agreement. Estimated small differences are caused by the different uncertainties of the used machines and by different methods of mathematical analysis of the detected raw data.

The standard for advanced technical ceramics ENV 843-4 of 1995 (Vickers, Knoop and Rockwell superficial hardness tests) was validated within the framework of the CERANORM EC-project. The paper reports on depth sensing hardness measurements done for comparison with the other hardness tests. The instrumented indentation test is a modern technique (recent issue ISO/DIS 14577) that has the potential to take into account the specific response of materials in a much better way. An evaluation has been made to establish whether the instrumented hardness technique is a appropriate method for advanced technical ceramics and offers potential for additional applications.

In order to validate the European standard ENV 843-4 for hardness test of advanced technical ceramics new reference materials were used during the SMT-project CERANORM. The tailored materials of Si3N4, SiC, or Al2O3 meet the requirements of the standards ISO 4547 and ISO 6507-3 for metallic materials and exhibit an improved surface quality with a roughness R-a less than or equal to 0.005 mum. In addition to the verification of the testing equipment, the reference materials are used for investigating scatter and reproducibility as well as for staff training. The training on materials with a representative indentation behaviour gives good experience and assists the appropriate choice of equipment and testing procedure.

To validate the European standard ENV 843-4 for hardness measurements on ceramics, three classes of ceramic materials, silicon nitride, silicon carbide, and aluminium oxide, involving 19 ceramics in total, were tested using the traditional techniques Vickers (HV1), Knoop (HK2), and superficial Rockwell (HR45N). The use of new ceramic reference blocks certified according to the standards ISO 4547 and ISO 6507-1 for metallic materials was studied. If the hardness response of the tested materials does not involve chipping and cracking the application of high hardness reference blocks for training users to obtain hardness values comparable with the certified HV1 and HK2 values improves the reproducibility from about 10% to 1 to 3%. The scatter between the laboratories is similar to the scatter within the laboratories. The measurement of the indentation geometry on typical commercial ceramic materials can be made only with higher scatter and reduced reproducibility compared with typical metallic materials, which is caused by the stochastic indentation response. For such materials involving chipping and cracking (for instance SiC), the application of reference blocks with well-shaped indentations does not provide improved comparability of results between the laboratories. The actual indentation response of the ceramic material tested must be considered before selecting the appropriate hardness technique and test force. There is no significant difference between the abilities of the hardness techniques HV1, HK2, and HR45N to discriminate sensitively between materials of closely similar properties.

This contribution gives a survey about the development of a standard for the "Force-indentation depth-measuring principle" at the national and international levels. Additionally, informations about the differences between the basic German Standard and the current ISO Draft Standard as well as about the experiences in application of the instrumented indentation test, in particular regarding the effect of test piece roughness, the availability of reliable testing machines and the behaviour of advanced ceramic materials.

ISO-Standardization and Application of the Instrumented Indentation Test. This contribution gives a survey about the development of a standard for the Force-indentation depth-measuring principle at the national and international levels. Additionally, informations about the differences between the basic German Standard and the current ISO Draft Standard as well as about the experiences in application of the instrumented indentation test, in particular regarding the effect of test piece roughness, the availability of reliable testing machines and the behaviour of advanced ceramic materials.

Using the statistical approach of the ISO-Guide to measurement uncertainty (1992) the evaluation of uncertainty of tensile/compression testing machines is described. The practical approach involves the relevant uncertainty contributions including the reference equipment, the properties of the machine to be verified and finally the properties of the specimen to be tested. Compliance testing according to machine classes that includes the uncertainty of machine calibration turned out to become a general requirement of DIN ISO 17025, The machine parameters are exemplary used calculating the uncertainty of tensile test results such as tensile strength and yield strength. These uncertainties are related to data of a national round robin test in 1997 and show good correspondence within the accuracy of the present procedure.

The round robin has been conducted according to ENV 843-4 for Knoop hardness at 9.81 N on several commercial advanced technical ceramics. The test has been designed to discriminate between the scattering caused by the laboratories, separated into indenting and measuring, by the response of the ceramic material, and by the specific specimen. The test has confirmed that the Knoop hardness can be used for the characterization of technical ceramics but neither of the tested materials is appropriate to be used as reference material for Knoop hardness.

The time strength behaviour of alkali silicate glasses depends on the environmental media and external stresses during aging as well as on the type of initial crack (kind of damage). An extended crack growth model based on the competing processes of crack growth and its retardation due to stress-enhanced alkali leaching in moist media has been implemented on a computer. Considering residual contact stresses, this model is able to simulate crack arrest, strength increase (or decrease, respectively) during aging under load, static and dynamic fatigue including strength distributions of various soda-lime-silica glass applications. Lifetime prediction of static fatigue can be improved up to about 10 years.

For analysing the recording microindentation tests four different two-parametric functions (two kinds of polynomials of second order, a linear function of the inverse penetration depth, and the power law) are involved. Four silicate glasses and two sintered materials are investigated in the range of 0.1 to 100 N and 1 to 35-mu-m. To study the statistical fluctuations of the fitting parameters 27 indentation curves are recorded for each specimen. The results show that the different recording hardnesses are interrelated with each other via the position of the depth origin related to the maximal penetration depth. The variation coefficients of the recording hardnesses (terms of second order) are much less (< 5%) than those of the second fitting parameters (> 10%) (for example, the position of the depth origin). Minimal fluctuations are achieved using the purely quadratic dependence of load on the depth. Taking into account the elastic recovery the Vickers hardness calculated from the recording hardness is nearly equal to the Vickers hardness measured optically. The residual deviation indicates little additional deformations within the fixing of the indenter.

The crack initiation threshold F(c), which is determined using the Vickers indentation technique, was used to estimate abrasion strengths of different fused alumina abrasive grains. Assuming Weibull distributed strength, the dependence of the crack initiation probability on the indentation load F according to F-1/4 was verified. The crack initiation thresholds of Al2O3 crystals correlate with the strengths of the abrasive grains which were determined by static and dynamic methods.The contents of chromium, iron, manganese and titanium in the alumina crystals were estimated by electron paramagnetic resonance and energy dispersive X-ray spectrometry measurements; the results indicate that the crack initiation thresholds are not essentially determined by these impurities.