An abnormal displacement change during holding period in nanoindentation tests on zirconia dental ceramic

Abstract

An abnormal displacement change observed during the holding period in nanoindentation tests on a zirconia dental ceramic was reported in this paper. It was found that, at the initial stage of the holding period, the measured displacement versus time curves were similar in shape with the typical indentation creep curve reported in previous studies. As the holding lasted for long time, however, an evident reduction in displacement was observed for tests with high loading rate, implying that another unknown process, which might result in a decrease in displacement, would co-exist with creep during holding period. Elastic recovery was suggested to be one of the possible sources for such a displacement reduction. An empirical method was also proposed to eliminate the effect of this displacement reduction on the determination of hardness and Young's modulus.

Effect of experimental conditions on nano-indentation response of low density polyethylene (LDPE)

“…[7] Such analysis is very easy for elastic-plastic material but for materials having time-dependent behavior, this technique becomes delicate as models for mechanical characterization of such materials are not well developed. [8] The load is applied on the sample through the indenter for a particular period of time and the resultant indentation size is measured as in a conventional normal indentation test. The contact compliance method has been recently used for hardness and modulus computation; this method is based on the imposed displacement/reaction force response.…”

“…YC Lin [7] investigated the effect of different holding times on the nano-mechanical properties of ductile and brittle materials. Zhang et al [8] studied the effect of holding time in nano-indentation tests on zirconia dental ceramic. Chudoba et al [20] worked on different substrates (steel, nickel, glass) and film combinations (diamond-like carbon, Al 2 O 3 , aluminum, gold) to study creep effects on modulus and hardness.…”

Effect of colourants on the optical characteristics and structure of Y2O3 stabilised tetragonal zirconia ceramic

“…Therefore, in this experiment, the thickness of the Y‐TZP test piece was selected to be 1 mm. Studies have shown that the thickness of a porcelain layer of 1 mm has a transmittance of about 40%, 27,28 so this thickness is also the conventional thickness of ceramic materials for transmission.…”

Effect of Fe2O3 and CeO2 on Transmittance of Y2O3 Stabilized Tetragonal Zirconia Polycrystals

“…Therefore, in this experiment, the thickness of the Y-TZP test piece was selected to be 1 mm. Studies have shown that the thickness of a porcelain layer of 1 mm has a transmittance of about 40% [24,25], so this thickness is also the conventional thickness of ceramic materials for transmission.…”