Input error sensitivity of hardness and elastic modulus evaluated from indentation load-displacement records by Oliver and Pharr method

Due to its straightforwardness and the ease of implementation the Oliver-Pharr method [1] has been used in the analysis of load-displacement records for more than a decade now. This paper provides analytical expressions relating the errors in the hardness and elastic modulus obtained by this method to systematic calibration errors of measured depth, force and frame compliance for spherical and sharp indentation. While in systems with zero frame compliance the sensitivity ratios for depth and force measurement were found to be constant, in systems with a finite frame compliance the error sensitivity changes with the absolute values of applied force and measured depth. The analytical predictions are compared with the true variation in derived materials parameters and the ranges of validity of the expressions are established. The error sensitivity with respect to different input variables and its implications for the actual measurement are discussed.     

M. Carey Lea, the first mechanochemist

The experiments of M. Carey Lea (1823-1897) are usually considered the first systematic investigations on the chemical effects of mechanical action. This paper collects the most important facts about Lea's life and discusses his research from the point of view of mechanochemistry. Lea was born into a family of considerable privilege and exceptional achievements. He suffered from weak health throughout his life. Consequently, he was educated at home by a tutor and later worked in the private laboratory of his home in Philadelphia. Lea was primarily a photochemist, his first mechanochemical observation in 1866 concerned the pressure sensitivity of photographic plates. Later in his life, he investigated the effect of various kinds of energy—heat, light, mechanical action—on allotropic (colloidal) silver and silver halides. The “parallelism” of the results motivated Lea to study the mechanochemical decomposition of dozens of stable compounds between 1892 and 1894. He observed the decomposition of silver and mercuric chlorides by trituration in a mortar, although the same compounds are known to melt or sublime undecomposed when heated. Lea was elected member of the National Academy of Sciences in 1892.     

Use of polymers for cement-based structural materials

Cement-based materials are widely used in the civil infrastructure. Polymers as admixtures can improve the properties, particularly in relation to water absorption reduction, toughness enhancement, vibration damping and increase of the bond strength of cement to reinforcements. Polymeric admixtures include particles, short fibers and organic liquids. Latex in the form of an aqueous particle dispersion is most common. Other than being used as admixtures, polymers are used as partial replacement of fine aggregate, for coating, sealing and repairing concrete and for coating steel reinforcing bars for corrosion protection.     

Surface Activation of Diamond Particles in the Process of Chemical Coppering

The effect of the composition of sensitizing–activating solutions on the activation efficiency and the chemical coppering of diamond powders is studied. The results demonstrate that stabilizing additives improve the stability of the solutions, influence the average coppering rate, and play a key role in determining the morphology and quality of the resultant coatings. The most effective stabilizing additive is synthamid-10, which ensures the deposition of high-quality copper coatings.