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Erika CsehovAaA, Jana AndrejovskAaA, Apichart Limpichaipanit, Ján Dusza and Richard Todd

Indentation Load-Size Effect in Al2O3 — SIC Nanocomposites

The indentation load-size effect (ISE) in Vickers hardness of Al2O3 and Al2O3 + SiC nanocomposites has been investigated and analysed using Meyer law, proportional specimen resistance (PSR) model and modified proportional specimen resistance (MPSR) model. The strongest ISE was found for alumina. Both the PSR and MPSR models described the ISE well, but the MPSR model resulted in slightly lower true hardness values for all materials investigated. No evidence of the effect of machining stresses on the ISE has been found.

Open access

Jozef Petrík and Pavol Palfy

Indentation Size Effect in Low-load Vickers Hardness Testing of Ceramics. Journal of the European Ceramic Society , 19, 2625 - 2631. Sangwal, K., Hordyjewicz, M., Surowska, B. (2002). Microindentation hardness of SrLaAlO 4 and SrLaGaO 4 single crystals. Journal of Optoelectronics and Advanced Materials , 4(4), 875-882.

Open access

J. Petrík

Abstract

The influence of applied loads between 0.09807 N and 0.9807 N on measured values of micro-hardness was evaluated by Meyer’s index n, proportional specimen resistance model (PSR) and Hays – Kendall methods, Total Dispersion Zone and Analysis of Variance (ANOVA). The measurement was repeated 6 times using the same hardness reference block with standard hardness Hc = 327 HV0.05 as a sample. The influence of the load on the measured value of micro-hardness is statistically significant, and the relationship between applied load and micro-hardness manifests reverse indentation size effect (ISE) for most of “measurements”. The high value of the uncertainty of results can affect the existence and nature of ISE, especially at low loads.

Open access

W. Żórawski, M. Makrenek and A. Góral

Abstract

Nanostructured and composite WC-12Co coatings were prepared by means of the supersonic spray process (HVOF). The microstructure and composition of WC-12Co nanostructured powder were analyzed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Investigations revealed nano grains of WC with the size in the range of 50-500 nm. The nanostructured sprayed coating was analysed by SEM and phase composition was investigated by X-ray diffractometer (XRD). A denser coating structure with higher hardness was observed compared to conventional coating with a small amount of W2C, WC1−x, W and some amorphous phase. Young’s modulus and hardness were determined by depth sensing indentation in HVOF sprayed WC-12Co nanostructured coatings. Results were compared to conventional coatings and the relevance of the nanostructure was analyzed. An indentation size effect was observed on the polished surface and cross-section of both coatings. Data provided by indentation tests at maximum load allow to estimate hardness and elastic modulus. Enhanced nanomechanical properties of conventional coating in comparison to nanostructured one were observed. Nanostructured coatings WC-12Co (N) revealed significantly better corrosion resistance.

Open access

U. Kanders and K. Kanders

behavior using nanoindentation. Surf. Coat. Tech., 200 , 3459–3467. 5. Michel, J.P., Ivanovska, I.L., Gibbons, M.M., Klug, W.S., Knobler, C.M., Wuite, G.J.L., & Schmid, C.F. (2006). Nanoindentation studies of full and empty viral capsids and the effects of capsid protein mutations on elasticity and strength. Proc. Natl. Acad. Sci. USA, 103 , 6184–6189. 6. Sangwal, K. (2000). On the reverse indentation size effect and microhardness measurement of solids. Mater. Chem. Phys., 63 , 145–152. 7. Kanders, U., Kanders, K., Maniks, J., Mitin, V., Kovalenko, V

Open access

Uldis Kanders and Karlis Kanders

using nanoindentation. Surf. Coat. Tech., 200 , 3459–3467. 5. Michel, J.P., Ivanovska, I.L., Gibbons, M.M., Klug, W.S., Knobler, C.M., Wuite, G.J.L., & Schmid, C.F. (2006). Nanoindentation studies of full and empty viral capsids and the effects of capsid protein mutations on elasticity and strength. Proc. Natl. Acad. Sci. USA, 103 , 6184–6189. 6. Sangwal, K. (2000). On the reverse indentation size effect and microhardness measurement of solids. Mater. Chem. Phys., 63 , 145–152. 7. Kanders, U., & Kanders, K. (2017). Nanoindentation response

Open access

Mateja Egart, Biljana Janković and Stane Srčič

Powder Compaction Technology, 2nd ed., Informa Healthcare, New York 2011. 30. X. Cao and M. A. Morganti, Study of Hiestand’s “Special Case” Pharmaceutical Materials Using AFM Nanoindentation, 2009, AAPS Annual Meeting and Exposition. 31. D. Olusanmi, K. J. Roberts, M. Ghadiri and Y. Ding, The breakage behaviour of Aspirin under quasi-static indentation and single particle impact loading: Effect of crystallographic anisotropy, Int. J. Pharm. 411 (2011) 49-63; DOI: 10.1016/j.ijpharm.2011.03.039. 32. C. C. Kwan, Y. Q. Chen

Open access

A. Arputha Latha, M. Anbuchezhiyan, C. Charles Kanakam and K. Selvarani

are depicted in Fig. 10 . It is clear that the microhardness number increases with increasing load. Fig. 10 Microhardness number vs. load for GG (a) (−1 0 1) plane, (b) (1 −1 1) plane and (c) (0 1 1) plane. It is evident from the above plot that the microhardness value of the crystal increases with an increase in load which is in agreement with the reverse indentation size effect (ISE) [ 12 ]. Hardness values of γ-glycine crystal differ from one plane to another, which confirms the microhardness anisotropy. For example, it is clear from Fig. 8 that

Open access

V. Rizov

. Strenthening of Unreinforced Masonry Walls using FRPs. ASCE , 5 (1996), No. 2 , 76-84. Tumialan, J., N. Galati, A. Nanni. Fiber-Reinforced Polymer Strengthening of Unreinforced Masonry Walls Subject to Out-of Plane Loads. ACI Structural Journal , 99 (2003), No. 4 , 321-329. Busschen, A. Micromechanical Modelling of Uni-directional Glass Fiber Reinforced Polyester: Effect of Matrix Shrinkage, In: Proc. Euromech Colloquim 269, (Ed. A. Vautrin), France, St. Etienne, 1991, 1-8. Zhang, L., L

Open access

Mohd Anis, S.S. Hussaini, M.D. Shirsat and G.G. Muley

evidences the presence of chlorine in the sample [ 9 ]. The large multinucleations were observed on the crystal surface which might have occurred due to organic dopant LA. The absence of cracks and voids confirm the perfection of LA-ZTC crystal. 3.2 Microhardness studies The Vicker’s microhardness study has been done using a Shimadzu HMV-2T microhardness analyzer to assess the mechanical properties of LA-ZTC crystal. The Vicker’s hardness number (VHN) of LA-ZTC crystal has been determined at different indentation loads using the relation: H v = 1.8544 P/d 2 kG