scholarly journals Low impact surface hardness testing (Equotip) on porous surfaces - advances in methodology with implications for rock weathering and stone deterioration research

2016 ◽  
Vol 41 (8) ◽  
pp. 1027-1038 ◽  
Author(s):  
Katrin Wilhelm ◽  
Heather Viles ◽  
Órlaith Burke
Keyword(s):  
Surface Hardness ◽  
Rock Weathering ◽  
Hardness Testing ◽  
Impact Surface ◽  
Porous Surfaces ◽  
Stone Deterioration

scholarly journals Self-disinfecting Alginate vs Conventional Alginate: Effect on Surface Hardness of Gypsum Cast—An in vitro Study

2017 ◽  
Vol 18 (11) ◽  
pp. 1061-1064 ◽  
Author(s):  
Ajay Nagpal ◽  
Ranjith Madhavan ◽  
Navia George ◽  
Niharika R Thummala ◽  
SV Ravi
Keyword(s):  
Stainless Steel ◽  
Clinical Practice ◽  
Infection Control ◽  
Clinical Significance ◽  
Surface Hardness ◽  
In Vitro Study ◽  
Hardness Testing ◽  
Testing Data ◽  
The Mean

ABSTRACT Introduction For the construction of any dental prosthesis, accurate impressions are necessary. Hence, we undertook the present study to evaluate and compare the surface hardness of gypsum casts poured from impressions made using conventional alginate and self-disinfecting alginate. Materials and methods A total of 30 impressions of stainless steel die were made, out of which 15 impressions were made with conventional alginate and 15 were made with selfdisinfecting alginate and poured using Type III dental stone. Thirty stone specimens were subjected for hardness testing. Data were analyzed using independent samples t-test to compare the mean surface hardness. Results Difference in surface hardness was statistically insignificant (p > 0.05). Conclusion Surface hardness of gypsum casts poured using impressions made from self-disinfecting alginate and conventional alginates were comparable. Clinical significance Self-disinfecting alginates may be employed in clinical practice as safe and effective materials to overcome the infection control issues without compromising on the properties of the material. How to cite this article Madhavan R, George N, Thummala NR, Ravi SV, Nagpal A. Self-disinfecting Alginate vs Conventional Alginate: Effect on Surface Hardness of Gypsum Cast—An in vitro Study. J Contemp Dent Pract 2017;18(11):1061-1064.

The Influence of Plasma Nitriding Period on Nitrided Layers Thickness

2016 ◽  
Vol 258 ◽  
pp. 395-398 ◽  
Author(s):  
Ondrej Pilch ◽  
Vojtěch Hruby
Keyword(s):  
Optical Microscopy ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Surface Hardness ◽  
Experimental Methods ◽  
Nitriding Process ◽  
Material Surface ◽  
Hardness Testing ◽  
Surface Layers ◽  
Cross Sectional

The plasma nitriding as a technology for finishing of material surface layers was carried out on selected material. The effect of plasma nitriding conditions on the thickness and hardness of nitrided layer was investigated. The influence of plasma nitriding period on the thickness of the plasma nitrided layers was comprehensively assessed on the C55 steels. Plasma nitriding was carried out on selected material at 500 °C under 280 Pa with a mixture atmosphere of H2 and N2 in the plasma nitriding equipment. The period of the plasma nitriding process was changeable from 5 to 20 hours. Measurements of the properties of nitrided layers of selected material were solved by using experimental methods in accordance with standards. The samples were characterized by GDOES spectrometry, optical microscopy, and hardness testing. The depths of the plasma nitriding layers were also detected using cross-sectional microhardness profiles. Relation between plasma nitriding period and a thickness of a nitrided layer was explained and has shown that microhardness and surface hardness of mentioned samples were significantly increased.

Effect of CeO2 on Microstructure and Hardness of Roller Surface Alloyed by Laser

2012 ◽  
Vol 155-156 ◽  
pp. 877-880
Author(s):  
Huai Jun Yue ◽  
Qi Bin Liu
Keyword(s):  
Co2 Laser ◽  
Testing Machine ◽  
Surface Hardness ◽  
Service Performance ◽  
Micro Hardness ◽  
Rockwell Hardness ◽  
Hardness Testing ◽  
Coating Materials ◽  
Hardness Tester ◽  
Molten Liquid

To improve the service performance of roller. The surface of roller was alloyed by a 5kW CO2 laser. The effect of CeO2 on microstructure and hardness was studied by means of OM, Micro-hardness Testing Machine and Rockwell hardness tester. The results indicate that addition of CeO2 into coating materials can enhance the fluidity of molten liquid, refine and purify microstructure and increase microhardness and surface hardness of alloying coating.

scholarly journals UNDERSTANDING THE REBOUND SURFACE HARDNESS OF CONCRETE

2015 ◽  
Vol 21 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Katalin Szilágyi ◽  
Adorján Borosnyói ◽  
István Zsigovics
Keyword(s):  
Compressive Strength ◽  
Young’S Modulus ◽  
Material Properties ◽  
Young's Modulus ◽  
Experimental Studies ◽  
Surface Hardness ◽  
High Strength ◽  
Hardness Testing ◽  
Technical Literature ◽  
Two Parameter

Surface hardness testing of materials can be considered as the oldest method to get information about strength related material properties. In recent decades the rebound hammer has been the most popular surface hardness testing device for concrete uniting the advantages of its predecessors. In the technical literature numerous proposals are available for simple, two-parameter regression analyses of rebound surface hardness vs. compressive strength relationship of concrete. The remarkable diversity of the proposed curves implies the need of the more than two-parameter regression techniques to reveal the most pronounced parameters governing hardness behaviour. The objectives of present experimental studies were to carry out dynamic and static hardness tests, Young’s modulus and compressive strength tests on concrete specimens. From the development of the tested properties with time it can be concluded that the rebound hammers provide a hardness value for high strength concretes connected to the Young’s modulus rather than the compressive strength. Present paper includes a parametric simulation and a parameter fitting of the verified phenomenological constitutive model of the authors which recognizes the w/c ratio as the main driver of the interrelated material properties and gives a realistic formulation for the time dependent behaviour of the rebound surface hardness of concrete.

On a Testing of Mechanical Properties of Material Surfaces

2005 ◽  
Vol 482 ◽  
pp. 399-402
Author(s):  
L. Berka ◽  
N.V. Murafa
Keyword(s):  
Surface Hardness ◽  
Hardness Test ◽  
Accurate Method ◽  
Material Surface ◽  
Hardness Testing ◽  
Contact Loading ◽  
Testing Method ◽  
Bending Stresses ◽  
Microcrack Formation ◽  
Vickers Hardness Test

Hardness testing is a method frequently used for evaluating the resistance of body surfaces to the influence of contact loading. The Vickers hardness test is applied for this purpose in a case when the material is sufficiently ductile and no cracks occur in the corners of the indents. Testing of the surface hardness of such materials as glass and ceramics on the basis of the Vickers testing method must take into account the energy that is spent on crack spreading. This paper describes a more exact and accurate method for evaluating resistance to microcrack formation on the surface of a material. To evaluate the conditions for crack spreading, it is necessary to test a specimen under loading in bulk. The suggested procedure involves a bent strip. As bending stresses are known, from them and from the differences in crack length along and across the strip, the resistance of the material surface to crack propagation is determined.

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