Metal hardness differences

Eddy-Current Methods This is one of the earliest NDT methods and is still used Basically, this method reveals any differences tn electrical impedance between parts to be tested and a reference sample. Parts to be examined are passed through a coil or explored with a probe, and a trace appears on a CRT, Since magnetic and electrical characteristics are closely related to metallurgical quantities, a trace position or pattern or a meter reading clearly shows variations in metal hardness and composition, as well as defects. Both ferrous and nonferrous parts can be tested, and various coils, probes, and detector lips are available,... 

Massive electrochemical attack known as galvanic corrosion [58,59] is the most severe form of copper corrosion. It can completely remove the copper from the structures (Figs. 17.25 and 17.26). It can occur when the wafers are exposed to a corrosive electrolyte for an extended period. It can also occur if the slurry does not contain enough or effective corrosion inhibitor. The source of such a galvanic potential on the patterned copper surface may be due to the fact that some copper structures connected to transistors have a different electrical potential than the rest of the wafer surface. Another possible cause of this type of galvanic potential is related to the barrier material induced metal metal battery effect. Most copper CMP slurries have been developed for Cu structures with Ta or TaN as a barrier material. In some cases, other metals may also be used in addition to the barrier metal. For example, a metal hard mask could contribute to the galvanic corrosion effects. It is also possible that some types of copper are more susceptible to corrosion that others. The grain... 

Welding results in a metallurgical discontinuity with different microstructures than the parent metal. Mechanical properties of the weld metal usually differ. Even with PWHT, weldments retain a residual stress field. Heat affected zones often contain a coarsened grain structure and/or hard spots. Corrosion testing of the welds may be a critical part of the testing program. 

TABLE 8.3. Real Area of Contact at Different Loads for Four Metals of Different Hardness... 

Most cBN deposition experiments reported so far were carried with silicon substrates. Only a few papers concerned non-silicon substrates. Mirkarimi et al. [46] used different metallic substrates and found a decrease of the cBN content with decreasing metal hardness. Schiitze et al. [47] found that it is not possible to deposit cBN films on steel substrates under conditions which are suitable for silicon substrates. On steel cBN could only be prepared after deposition of a high-density hBN buffer layer. Concerning the effect of the substrate material on the cBN film growth there are still a lot of open questions. 

As it is also known from other fields of working metals, the different forms of the chips from machining cast iron and steel cause a much more intense interaction with the cutting plate for the latter material. Therefore, the demands concerning the chemical and oxidation stability are more stringent on working hardened steel than on machining hard cast iron (Table 2). 

It is well-known that an increase of water hardness decreases metallic toxicity. For instance, LC50 of zinc during 96 h of an acute toxicity test with brown trout is 0.14 mg/L when the hardness is 10 mg/L CaCOs, and it rises to 1.0 mg/L when the hardness is 204 mg/L CaCOa [12]. The same effect of the hardness on the metallic toxicity is also reported in rainbow trout [29]. However, the effect of the hardness differs depending on the types of metals. The increased hardness weakened the... 

A beneficial property of elastomers is that they can be compounded or joined with other materials to strengthen certain characteristics. Other kinds of polymers may be installed next to various other materials, such as metal, hard plastic, or different kinds of rubber, with excellent adhesion. Harper CA (ed) (2002) Handbook of plastics, elastomers, and composites, 4th edn. McGraw-Hill, New York. Harper CA (ed) (2002) Handbook of plastics, elastomers, and composites, 4th edn. McGraw-Hill, New York. Elias HG et al. (1983) Abbreviations for thermoplastics, thermosets, fibers, elastomers, and additives. Polym News 9 101-110. James F (ed) (1993) Whittington s dictionary of plastics. Technomic Publishing Co. Inc., Carley. Harper CA (ed) (2002) Handbook of plastics, elastomers, and composites, 4th edn. McGraw-Hill, New York. Skeist I (ed) (1990) Handbook of adhesives. Van Nostrand Reinhold, New York. 

Changing material of construction (such as piping, gaskets, valve packing, fasteners, substituting metals with different hardness, heat treatment, or metallurgy) ... 

Yoshida and coworkers discuss densification of glasses caused by indentation [8]. Now consider the finding Bhushan e.a. [9] that microhardness measurements of worn metal samples show a 10-80 % increase of hardness in the worn layer. While behavior of the metals is different from that of polymers since the latter are viscoelastic, a possible connection between the characteristics of groove profiles we have obtained with hardness determination seemed worth pursuing. 

Among the metals, for example, sodium and potassium are similar to each other and form similar compounds. Copper and iron are also metals having similar chemical properties but these metals are clearly different from sodium and potassium—the latter being soft metals forming mainly colourless compounds, whilst copper and iron are hard metals and form mainly coloured compounds. 

Anisotropy in metals and composite materials is common as a result of manufacturing history. Anisotropic materials often display significantly different results when tested along different planes. This appHes to indentation hardness tests as well as any other test. 

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