Using the ratio: maximum load over unload stiffness squared, Pm/Su², on the evaluation of machine stiffness and area function of blunt indenters on depth-sensing indentation equipment
Abstract:Depth sensing indentation study was conducted in a Fischerscope H100V machine, equipped with a Vickers indenter with a tip roundness of approximately 1330 nm. Tests were carried out on soda-lime glass, fused silica, sapphire, aluminum (1100 alloy), high alloyed steel, titanium and copper. The widely used iterative method of Oliver and Pharr was unsuccessful in the attempts to analyze machine compliance and indenter area function. Therefore, an alternative procedure was adopted. The alternative procedure is bas… Show more
“…The nano-indentation test was carried out in a Fisher H100V equipment; a Vickers indenter with an area function previously calibrated was used [7]. To obtain the hardness and elastic modulus, the data was post-processed according to the Oliver and Pharr method [8].…”
Resumen-Las energía elasto-plásticas y el parámetro RID (Relative Indentation Depth: cociente entre la máxima profundidad de indentación y el espesor del recubrimiento, = hmax/t) se utilizaron para evaluar la capacidad de soportar carga de materiales con recubrimientos cerámicos. El estudio se realizó en sistemas sustrato-recubrimiento de TiN con espesores de 2 m y 3 m depositados por PAPVD sobre acero M2 y sobre acero inoxidable 304L. Se analizaron gráficos de dureza vs. y Wp/Wt vs. . Se encontraron correlaciones para diferentes profundidades de indentación a las que se da la transición entre la respuesta mecánica del recubrimiento y la respuesta mecánica del sistema sustrato-recubrimiento; y en los puntos donde la eficiencia de usar el recubrimiento cae al 33 y al 50%. Se demostró que puede obtenerse información importante a partir de los datos de energía sobre la respuesta mecánica de un sistema sustrato-recubrimiento, sin necesidad de recurrid al método de Oliver y Pharr para medir la dureza y el módulo de elasticidad.
Palabras clave-Energía de indentación, profundidad de indentación relativa (RID), recubrimientos duros.Abstract-The elasto-plastic energies and the RID parameter (Relative Indentation Depth =hmax/t), defined as the ratio between the maximum indentation depth and the coating thickness, were used to evaluate the ability of the ceramic coated systems to withstand load. The study was conducted on M2 and 304L steels coated with titanium nitride by PAPVD. Both substrates were coated with TiN of about 2,0 and 3,0 µm thickness. The hardness vs. () and the ratio of plastic to total energy (Wp/Wt) vs. () graphs were analyzed. There were found correlations between the indentation depths at which the transition from mechanical response due to the coating to the mechanical response of substrate-coating and to substrate dominated behavior and the depths at which the efficiency of using the coating falls 33% and 50 %. Results show that it is possible to get useful information from the energy taken from the mechanical response of the coated systems to avoid the Oliver and Pharr method for measuring the hardness and elastic modulus.
“…The nano-indentation test was carried out in a Fisher H100V equipment; a Vickers indenter with an area function previously calibrated was used [7]. To obtain the hardness and elastic modulus, the data was post-processed according to the Oliver and Pharr method [8].…”
Resumen-Las energía elasto-plásticas y el parámetro RID (Relative Indentation Depth: cociente entre la máxima profundidad de indentación y el espesor del recubrimiento, = hmax/t) se utilizaron para evaluar la capacidad de soportar carga de materiales con recubrimientos cerámicos. El estudio se realizó en sistemas sustrato-recubrimiento de TiN con espesores de 2 m y 3 m depositados por PAPVD sobre acero M2 y sobre acero inoxidable 304L. Se analizaron gráficos de dureza vs. y Wp/Wt vs. . Se encontraron correlaciones para diferentes profundidades de indentación a las que se da la transición entre la respuesta mecánica del recubrimiento y la respuesta mecánica del sistema sustrato-recubrimiento; y en los puntos donde la eficiencia de usar el recubrimiento cae al 33 y al 50%. Se demostró que puede obtenerse información importante a partir de los datos de energía sobre la respuesta mecánica de un sistema sustrato-recubrimiento, sin necesidad de recurrid al método de Oliver y Pharr para medir la dureza y el módulo de elasticidad.
Palabras clave-Energía de indentación, profundidad de indentación relativa (RID), recubrimientos duros.Abstract-The elasto-plastic energies and the RID parameter (Relative Indentation Depth =hmax/t), defined as the ratio between the maximum indentation depth and the coating thickness, were used to evaluate the ability of the ceramic coated systems to withstand load. The study was conducted on M2 and 304L steels coated with titanium nitride by PAPVD. Both substrates were coated with TiN of about 2,0 and 3,0 µm thickness. The hardness vs. () and the ratio of plastic to total energy (Wp/Wt) vs. () graphs were analyzed. There were found correlations between the indentation depths at which the transition from mechanical response due to the coating to the mechanical response of substrate-coating and to substrate dominated behavior and the depths at which the efficiency of using the coating falls 33% and 50 %. Results show that it is possible to get useful information from the energy taken from the mechanical response of the coated systems to avoid the Oliver and Pharr method for measuring the hardness and elastic modulus.
“…At least 15 indentation tests were conducted in each specimen for each value of peak load and only those curves within two standard deviations from the average P m /S 2 u ratio were used in the analysis of indentation data. 39 When true replicates are made under a given set of experimental conditions, the variation between their associated observations may be used to estimate the standard deviation of a single experimental condition. In this case, the statistical significance of the effects may be judged from an estimate of variance obtained by genuine replication.…”
In this work, the effects of conical indentation variables on the load-depth indentation curves were analyzed using finite element modeling and dimensional analysis. A factorial design 2 6 was used with the aim of quantifying the effects of the mechanical properties of the indented material and of the indenter geometry. Analysis was based on the input variables Y/E, R/h max , n, y, E, and h max . The dimensional variables E and h max were used such that each value of dimensionless Y/E was obtained with two different values of E and each value of dimensionless R/h max was obtained with two different h max values. A set of dimensionless functions was defined to analyze the effect of the input variables:, P 2 = h c /h, P 3 = H/Y, P 4 = S/Eh max , P 6 = h max /h f , and P 7 = W p /W T . These six functions were found to depend only on the dimensionless variables studied (Y/E, R/ h max , n, y). Another dimensionless function, P 5 = b, was not well defined for most of the dimensionless variables and the only variable that provided a significant effect on b was y. However, b showed a strong dependence on the fraction of the data selected to fit the unloading curve, which means that b is especially susceptible to the error in the calculation of the initial unloading slope.
“…Para calcular la dureza del material mediante la interfaz gráfica de usuario, se examina la curva de carga-descarga en el régimen elástico [29]. Se pueden obtener dos valores a partir de estas curvas: la penetración bajo carga máxima (hT) y la penetración final (hR) que se mide cuando el indentador está fuera de contacto con la muestra o material analizado.…”
En este trabajo se implementó el software de simulación para la nanoindentación de películas delgadas. El software desarrollado empleó la técnica de Dinámica Molecular. El modelo con el cual opera la interfaz gráfica (software), es un modelo aproximado, que reproduce las tendencias de las curvas características en pruebas de dureza de materiales. Por otro lado, el programa se diseñó y construyó con un entorno amigable, donde el usuario puede construir sus propias películas delgadas, tanto en monocapas como en bicapas. La interfaz permite controlar el espesor de la película, el número de capas y otras propiedades físicas tales como energía de disociación o parámetros de energía en la esfera; además, se puede tener control de los pasos de tiempo de dinámica. Para comprobar el funcionamiento del software se realizaron una serie de simulaciones utilizando los parámetros del cromo como material de referencia. Los resultados obtenidos, demostraron que el software puede reproducir las tendencias y curvas características en pruebas de dureza de materiales. Se espera mejorar este software para que sea una herramienta que permita realizar comparaciones con futuras investigaciones experimentales.
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