DOI: 10.1002/adem.201200214 Microstructure and Nanoindentation Properties of Surface Textures Obtained by Laser Machining and Molding in Silicon Carbide By Francesco Valentini, Italo Zambotto, Diletta Sciti, * Laura Silvestroni, Cesare Melandri and Stefano Guicciardi Silicon carbide is currently exploited in high temperature structural components as well as in wear resistant parts. The increasing demand for better performing components and low-cost automated processes is stimulating the investigation of post sintering surface treatments as an innovation of conventional mechanical finishing. Surface textures, such as regular arrays of holes, can markedly improve the tribological properties of silicon carbide-based components by enhancing its lubricating properties. [1,2] Laser machining is a flexible and non contact technique particularly suited for obtaining surface patterns, [3–16] and fabricating small diameter or high aspect ratio holes at designated locations. The possibility of controlling the technological parameters of radiation makes it possible to obtain unique surface structures and tailor the surface properties of the final products. Generally, the surface modifications induced by laser on ceramics depend upon: (a) processing parameters, such as laser wavelength and fluence, number of laser pulses and duration, spot size, beam homogeneity, beam angle of incidence, ambient pressure; (b) factors specific of the material, such as microstructure, composition, absorptivity coefficient, and thermal conductivity. [3–16] In this work, a pattern of holes in dense SiC components was obtained by both conventional molding and Nd:YAG laser machining. The component is a standard liquid phase sintered SiC, containing low percentages of sintering aids. The effects of laser machining of SiC has been reported by several authors that recorded a number of interesting features resulting from interaction between the laser beam and the ceramic, such as melting, vaporization, solidification of debris around the holes, as well as an extended heat affected zone (HAZ). [10–16] The purpose of this work is the evaluation of the effective damage induced by laser machining in the so-called HAZ through both microstructural investigations and nanoinden- tation tests in the area around the hole. In this respect, nanoindentation is a particularly suitable technique to locally characterize the material mechanical properties. [17] Young’s modulus and hardness, the two properties, which are commonly extracted by nanoindentation, are both influenced by any chemical or physical feature of the probed volume, in particular porosity. [18,19] For the sake of comparison, the same analyses are carried out on molded holes. Moreover, for the two types of component under examination, measures were carried out both around the holes and in the bulk of the component in order to point out any significant difference, which could derive from any variation of density, phase transformation, or microcracking. 1. Experimental 1.1. Materials and Hole Texturing The starting material is a commercial SiC by Meccano- tecnica Umbra SpA. For the reference materials, the holes array was produced by conventional molding, using a specifically designed mold. The texture was thus obtained in the green state prior to the sintering treatment. On the other COMMUNICATION [*] Dr. F. Valentini, I. Zambotto Meccanotecnica Umbra SpA, Via G. Agnelli, 7/9, 06042 Campello sul Clitunno (PG), Italy Dr. D. Sciti, Dr. L. Silvestroni, C. Melandri, Dr. S. Guicciardi CNR-ISTEC, Via Granarolo 64, 48018, Faenza (RA), Italy E-mail: diletta.sciti@istec.cnr.it A surface texture consisting of an array of holes in SiC components was obtained by either conventional molding in the green state or post sintering laser machining. According to microstructural analysis, very regular holes were obtained by laser machining with minimal microstructural damage. Irregular holes with defects and voids were instead found for the surface textures obtained via molding. Nanoindentation tests were performed in the areas close to the holes and no significant alteration of the mechanical properties was found after laser machining. 330 wileyonlinelibrary.com ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ADVANCED ENGINEERING MATERIALS 2013, 15, No. 5