Immunity from attack

Alloys containing more than 40% rhodium, while very difficult to fabricate, are almost immune from attack by aqua regia. The Pt— lORh alloy is particularly resistant to attack by free wet chlorine such as that produced by the combustion of halogenated organic vapours. 

As may be seen from the potential-pH diagram " (Fig. 6.3) platinum is immune from attack at almost all pH levels. Only in very concentrated acid solutions at high redox potentials (i.e. under oxidising conditions) is there a zone of corrosion. This accounts for the solubility of platinum in aqua regia. Platinum is also prone to complex-ion formation, and this can lead... 

Although deaerators provide the primary means of mechanical deaeration, they are not of themselves immune from corrosive attack. Acid condensate (or MU water that has been subjected to split-stream softening or dealkalization and remains acid due to a lack of pH adjustment) can damage the deaerator. 

Metals with protective oxide layers are not immune from attack, especially stainless steels and copper alloys, which may suffer aggressively from crevice corrosion. 

The relatively high yield of vinblastine from Catharanthus extracts and the remarkable biological activity of this alkaloid render this compound a natural choice for structural modification. Vinblastine is subject to attack by electrophilic reagents at a number of sites (Fig. 6), but by careful selection of reagents and conditions it is possible to operate in this structurally complex theater with considerable selectivity. Potentially electrophilic sites are, in some cases, immune from electrophilic attack. 

Air Ministry should collaborate in further trials aimed at obtaining information that would enable capital ships to be designed so as to secure the maximum immunity from air attack. ... 

The EPR technique has been used for other alloys as well, including cast (36) and wrought (37,38) duplex stainless, as well as Ni-base alloys (39). Lee (38) used DL-EPR testing to determine the minimum amount of Ti and/or Nb required to render Type 430 SS immune from intergranular attack. In some cases, the details of the experimental method (i.e., solution temperature, KCNS and H2S04 concentrations, scan range) must be modified to differentiate best the levels of sensitization of interest. For example, Scully and Kelly doubled the... 

An interesting aspect is that moths only thrive on keratin which contains disulphide bonds. If these are ruptured by reduction with sodium hydrosulphite and thioglycoUic acid and new links are built by methods such as joining primary amino groups with glyoxal, the wool is immune from attack by moths. 

The following regions are clearly outHned in F. 2.16 (i) immunity, in which the metal is considered to be immune from corrosion attack (ii) corrosion region, in which the metal corrodes and forms soluble species and (iii) passive region, in which the metal is coated with oxide or hydroxide. By decreasing the potential (cathodic protection), the metal can move from the active corrosion region to the immunity region. Zinc, because of its equiHbrium potential, is used as a sacrificial anode to protect the iron from corrosion. 

On September 11, 2001, the terrorist attacks on the World Trade Center Twin Towers and U.S. Pentagon ended America s illusion that the continental shores of the United States were immune from direct attack by terrorists. American society was forced to change in many significant ways, the most common of which is the extraordinary precautions taken to ensure the safety of airline passengers. More shocking news came out later when it was reported that terrorists could be planning attacks on chemical plants and oil refineries. 

Immunity region In the conditions of potential and pH of that region a metal is considered to be totally immune from corrosion attack and safe to use. Cathodic protection may be used to bring the potential of a metal closer to that region by forcing a cathodic shift, as shown for aluminum by the domain specified in Fig. 4.14 (or -1.0 to 1.2 V vs. CCSRE). 

Storage and distribution systems for phenol immunity from any form of attack ensures absolute product purity... 

Although it is one of the principles of war that civilians should not be the subject of attack, they have never been immune from the consequences of war. In the Second World War, in addition to the 20 million people who died in concentration camps, there were over eight million direct civilian casualties of the fighting. In an age of total war, non-combatants may in their way play as vital a part in the war effort as troops - indeed some countries may use civilians for tasks which elsewhere are performed by uniformed personnel. 

This chapter describes the general effects of chemicals on plastics and elastomers (elastomers) which will be referred to as polymers for brevity purposes. Even metals are not immune from attack by chemicals. Water corrodes iron, acids dissolve many metals. There is, however, a perception that metals are by and large not attacked by a large number of chemicals, starting with organic solvents. This perception is basically correct, but it does not apply to plastics. Solvents, acids, bases and other chemicals affect the overwhelming majority of polymers. 

Addition of about 0 04% arsenic will inhibit dezincification of a brasses in most circumstances and arsenical a brasses can be considered immune to dezincification for most practical purposes . There are conditions of exposure in which dezincification of these materials has been observed, e.g. when exposed outdoors well away from the sea , or when immersed in pure water at high temperature and pressure, but trouble of this type rarely arises in practice. In other conditions, e.g. in polluted sea-water, corrosion can occur with copper redeposition away from the site of initial attack, but this is not truly dezincification, which, by definition, requires the metallic copper to be produced in situ. The work of Lucey goes far in explaining the mechanism by which arsenic prevents dezincification in a brasses, but not in a-/3 brasses (see also Section 1.6). An interesting observation is that the presence of a small impurity content of magnesium will prevent arsenic in a brass from having its usual inhibiting effect . 

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