Metals erosion

This is an average value of metal erosion during the length of service and may vary with soil conditions. In coastal areas, for instance, where the subsoil water is saline, erosion of metal would be much more rapid and a further safety factor must be considered. Field experience will be a better guide to assess this. 

The erosion of metals varied depending largely on the melting point. For various metals erosion expressed in mm3 of metal removed from the orifice per 1 g of powder was ... 

Acid rain causes corrosion of some metals, erosion of marble (limestone), mortar etc. It is responsible for the destruction of softwood forests and for the pollution of ground water. 

The miscellaneous materials committees include paint, paper, packaging, rubber textiles, and plastics. The miscellaneous subjects committees include emission spectroscopy, fire standards, appearance of materials, microscopy, and resource recovery. The materials for specific applications committees include electronics, tires, consumer products, and food-service equipment. The corrosion, deterioration, and degradation of materials committees include corrosion of metals, erosion and wear, and durability of nonmetallic materials. 

At an early date it was observed that photodissooiation of adsorbed acetone 129) and biacetyl molecules 15) generated methyl radicals, which reacted with the surface of sublimed Bi or Sb, serving as adsorbents. From the spectral dependence of the metal erosion at the illuminated spot it could be ascertained that the maximum of the active spectral regions was markedly shifted to the red compared to that for the gas phase photodissociation. This implied a decrease of the required photon energy by an amount equivalent to about 1 ev, which was explained as a compensation effect, produced by the much stronger adsorption of the radicals, primarily formed (Section II, E). 

While the estimate of the latter needs information on factors such as surface soil enrichment of metal erosion rates, the former can be estimated roughly from the monitoring data. 

There are a wide range of substrates and films which can be produced as biomaterials. Metals such as titanium alloys are often used where high strength or toughness is required, such as hip implants. Their mechanical properties can be somewhat similar to bone, which makes them ideal candidates as structural bioimplants. However, as outlined by Skinner and Kay (2011), metal erosion can be a potentially dangerous problem. Ceramic films such as Ti02, Si02 or hydroxyapatite Caio(P04)6(OH)2 are often added to the surface to reduce wear of the implant and improve biocompatibUity. 

Material hardness For steels, hardening by working or by heat-treating has little effect on erosion resistance. For pure face centered cubic metals, erosion resistance increases with hardness. Thus, tantalum has twice the erosion resistance of aluminum. (Hardness for pure aluminum is 37 DPH, for tantalum the hardness is 70 DPH.)... 

J.S. Hansen, Relative Erosion Resistance of Several Metals, Erosion Prevention and Useful Applications, STP 664, ASTM, 1979, p148-162... 

In the presence of molten solder, the interface reactions include the simultaneous process of base metal dissolution or base metal erosion as well as intermetallic compound layer formation. The extent of dissolution depends upon the composition of the base metal as demonstrated in Fig. 9 for the case of molten 40Pb-60Sn solder and the base metals Au, Ag, Pd, Pt, Ni, and Cu [14]. The dissolution rate of Cu, specifically as a function of temperature for several molten Pb-Sn compositions is shown in Fig. 10 [15]. A lower Sn content reduces the extent of base metal dissolution. 

A low temperature imparts a metal erosion regime. With increase of temperature this metal erosion regime shifts to an oxide erosion regime via oxidation-affected erosion and oxidation-controlled erosion regimes. 

A higher feed rate extends the metal erosion regime and in turn alters the existence and extent of the other regimes. 

Oblique impact tends to reduce the extent of the metal erosion regime and promotes other regimes. 

Analysis of transition criteria for transition from metal erosion regime to oxide erosion regime... 

Schematic presentation of various erosion mechanisms at elevated temperature (a) metal erosion (b) oxide erosion (c) oxidation-affected erosion (d) oxidation-controlled erosion. 

It is stated that formation of various types of layers such as transfer layer, mechanically mixed layers, composite layer, etc., having characteristic composition and surface roughness governs the elevated temperature wear behaviour of metallic materials. Similarly during elevated temperature erosion, metallic erosion, erosion from the composite layer and erosion on the oxide scale are reported. The reported literature on abrasive wear at high temperature is much sparser and hence such layers are not yet found in the literature. The... 

The presence of an oxide scale is responsible for the existence of a variety of material removal mechanisms during elevated temperature erosion of metallic materials. These mechanisms have been carefully verified by experimental work. Four distinct material removal mechanisms, namely metal erosion, oxidation-affected erosion, oxidation-controlled erosion and oxide erosion, have been experimentally established. These experimental observations have been substantiated by theoretical considerations. A suitable criterion for transition from one erosion regime to another regime is yet to evolve. Attempts have been made to analyse such transitions using preoxidized sanities. 

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