Agilent 5991-3250EN The Revolutionary Impact of the Oliver and Pharr Technique on the Science of Hardness Te free download

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Keysight Technologies The Revolutionary Impact of the Oliver and Pharr Technique on the Science of Hardness Testing Application Brief Abstract Background on Vickers Hardness limited by one's ability to measure the diagonals of the indentation. ASTM E384- Prior to the advent of instrumented 11 recommends that the test not be used In 1992, Warren Oliver and George Pharr indentation, the Vickers hardness test published an article in the Journal of unless it produces an indentation having was the state-of-the-art in microhard- diagonals of 17m or greater. If the Materials Research that revolutionized ness testing. The Vickers hardness test hardness testing [1]. According to Thomas indented material is actually a coating, is still used today and is governed by two this same standard recommends that the Reuters Web of Knowledge, this article standards: ASTM E384 and ISO 6507. has been cited more than 8,500 times, indentation depth be less than 10% of the The test involves pressing a Vickers coating thickness. Taken together, these making it one of the most cited works indenter (an oblique, four-sided pyramid) in all of material science. The genius of two requirements imply that the Vickers into a surface to a speciic force, P, and hardness test should not be used at all Oliver and Pharr was this: they devised holding that force for 10 seconds. Once a way to know the size of a hardness for coatings which are less than about the indentation process is complete, the 60 m thick. indentation without imaging it. This de- lengths of the diagonals of the indenta- velopment disrupted Vickers and Knoop tion are measured optically in order to microhardness testing which required gage the size of the impression. Vickers The Origins of Instrumented direct measurement of the lengths of the hardness (HV) is deined as the applied Indentation i