Scratch-test,

Based on its apparent simplicity, scratch testing is frequently applied to estimate the cohesive and adhesion bond strengths of hydroxyapatite coatings (for example Arias et al., 2003 Zhang et al., 2006 Dudek and Adamczyk, 2013). However, the interpretation of the recorded traces is difficult as the test results are affected by scores of intrinsic and extrinsic parameters that tend to falsify the conclusion drawn. 

HAp coating and (b) fluoridated HAp coating on Ti6AI4V substrate. Point 1 denotes 

Scratch testing has been used to estimate the effect of addition to hydroxyapatite of reinforcing compounds such as Y-stabilised zirconia and alumina (Dudek and Adamczyk, 2013). A Revetest Xpress Plus device with a Rockwell indenter was used with progressive loads ranging from 1 to 200 N, a scratch length of 10 mm and a scratch rate of about 1.89 mm min-1. 

45% HAp+ 45% YSZ+ 10% alumina (d). (Images courtesy of Drs. A. Dudek and L. Adamszyk, Czfetochowa University of Technology, Poland. With permission by Optica Applicata.) 

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Ritzel, n. (Mach.) pinion, ritzen, v.t. crack slit scratch etch cut. RitzhlLrte, /. hardness to scratching, -probe, /. abrasive hardness test, scratch test, -priifer, m. abrasive hardness tester, aclerometer. -verfahren, n. = Ritzharteprobe. -zahl, /. (scratch) hardness number. 

Ritz-probe, /. scratch test or sample, -ver-such, m. scratch test. 

Burnett and Rickerby [78] and Bull and Rickerby [79] analyzed the scratch test of a coated sample and derived a relation between the critical normal load Wcr and the work of adhesion... 

A nano scratch tester (CSEM) was employed to carry out the scratch test. A Rockwell diamond tip with a radius of 2 fim was used to draw at a constant speed 3 mm/min across the coating/substrate system under progressive loading of 130 mN maximum at a fixed rate 130 mN/min. The total length of the scratch scar is 3 mm. The critical load (L ) here is defined as the smallest load at which a recognizable failure occurs. The failure can be observed both by the built-in sensors and by the optical microscope. 

Fig. 35—The typical optical microscopic images (500X) of the first crack in the scratch test.

Figure 33 shows a typical scratch test curve of Sample 4. Both the penetration depth and the residual depth as well as the tangential force can be obtained from this curve. The critical load can be found from the transition stages plotted in the three curves. The critical load (L ) of Sample 4 is 86.63 mN. 

Hard layer and soft layer combined together can reduce the intrinsic stress of the whole coating [17,18,22-27]. Samples 4, 5, and 6 have higher critical load than that of monolayer A and B. For Samples 5 and 6, no obvious crack occurs during the scratch test. Sample 5 has the highest hardness and reduced elastic modulus among the multilayer samples, and the interfaces in Sample 5 also contribute to scratch resistance. So it has the best micromechanical properties here. 

A Vickers diamond scratch test diamond load of the first visible scratch (by microscope)... 

The hardness of any solid can be assessed with testing equipment that measures the relative ease with which a surface can be either scratched or penetrated by another solid of known hardness. A long-used classification of the hardness of minerals, the Mohs scale of hardness, is based on the scratch test ten rather common minerals are arranged in the scale in order of their increasing relative hardness and listed in a scale varying from 1 to 10 (see Table 20). Each mineral in the Mohs scale scratches those with lower hardness numbers but does not scratch higher-hardness minerals. If a... 

Because of the simplicity of doing scratch tests, hardness has been an important diagnostic tool for mineralogists and prospectors by helping them to identify various rocks and minerals. 

Arai, Y., Sano, Y., Ito, K., Iwasaki, E., Mukouyama, T., and Baba, M. (1998). Eood and food additives hypersensitivity in adult asthmatics. 1. Skin scratch test with food allergens and food chaUenges in adult asthmatics. Arerugi 47, 658-666. 

Respiratory Effects. Scratch tests and intradermal tests were performed on a patient diagnosed with nickel-related asthma (McCoimell et al. 1973). Nonasthmatic controls were also tested. Testing resulted in respiratory distress in the patient but not in the controls, with a more severe response resulting from the scratch test. 

Abrasion resistance usually takes the form of a scratch test, in which the material is subjected to many scratches, usually from contact with an abrasive wheel or a stream of falling abrasive material. The degree of abrasion can be determined by loss of weight for severe damage, but is usually measured by evidence of surface marring. 

Scratch Test. The scratch microhardness test is a refinement of the Mohs test. The comer of a cubic diamond is drawn across the surface of a metallographically polished sample under a constant load, usually 29.4 N (3 kgf). The width of the resultant Vee groove scratch varies inversely with the hardness of the material displaced where H = scratch hardness number and A = groove width in micrometers. 

Hardness. The hardness of a mineral is its resistance to scratching. Testing for hardness is based upon Ihe premise that all minerals possess such resistance to a lesser or greater degree. The Mohs scale of hardness lias been universally adopted to test this physical properly. In Ihe list helow. the ascending numeric order of ihe mineral named will scratch all of those of lower order,... 

Although HIP treatment at 0.15 GPa induced almost no sintering, higher pressure and temperature conditions on the octahedral anvil apparatus improved compaction. Sintered samples (columnar, 3.4 mm OD X 5.0 mm long) prepared at 3 GPa and 823 K have good mechanical strength and hardness as determined by a conventional scratch test. 

A 59-year-old man developed urticaria while taking atorvastatin for hypercholesterolemia (18). Scratch tests with his medications gave a strong positive reaction only with atorvastatin. Atorvastatin was withdrawn and his urticaria resolved over the next 10 days. 

Figure 47 Schematic app (f) and 7app (f) for the electrochemical scratch test. Once the return potential exceeds Erp, the current increases. The size of the step (50 mV in this case) will define the uncertainty of the measurement of rp.

Fig. 2 Typical contact geometries used for scratch testing. The average strain is proportional a to tan9 in the case of conical or pyramidal indentors and b to a/R in the case of spherical indentors...

Some difficulties also arise for the interpretation of scratch tests carried out at progressively increasing normal load or indentation depth. Figure 3 indicates, for example, that a transition from ductile deformation to brittle cracking can occur when increasing the normal load whilst the contact strain is nominally fixed by the conical indenter angle. This is indeed observed in many polymer systems and the notion of a critical load at the ductile-brittle transition is largely used to characterize the scratch response. This depth... 

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