Types of Hydrogen Damage

The body-centered crystal structures of carbon and low-alloy steels are susceptible to four types of hydrogen damage, two of which are low-temperature processes and two are high-temperature processes ... 

Specific types of hydrogen damage, some of which occur only in specific alloys under specific conditions include ... 

Another common type of DNA damage is due to the formation of thymine dimers induced by ultraviolet and ionizing radiation. These intrastrand covalent bonds form a cyclobutyl ring between the C-5 and C-6 of one thymine, and the same carbons on the adjacent thymine. The result is that the DNA backbone on the thymine-containing strand is structurally altered, which may cause disruption of the hydrogen bonds with the corresponding adenine residues on the complementary strand (Fig. 23.2.). 

There are few if any favorable effects of hydrogen in materials, while numerous types of mechanical damage may... 

When bleaching is requited, a reductive bleach with sodium hydrosulfite and sodium metabisulfite is used. Cotton blends may requite a hydrogen peroxide bleach at pH 9.0—9.5 prior to or iastead of the normal reductive bleach. Chlorine-type bleaches which damage elastomeric fibers are avoided. 

Types of Damage. Hydrogen attack is characterized by three types of damage, as follows ... 

In high-pressure boilers, there are three types of on-load corrosion acidic chloride, neutral chloride/dissolved oxygen, and caustic attack. The first and second (once it becomes established) are brittle and thick-walled and are accompanied by hydrogen damage which can lead to failure within a few hundred hours. Caustic attack tends to produce a gouged appearance of the metal due to extensive wastage. The morphology is fairly characteristic of the failure type. Acidic chloride forms hard, laminated oxide, whilst, with caustic attack, the oxide is often soft, and, as it is easily removed, may be absent. 

NOTE With these types of programs, free sodium hydroxide is not formed, even in the event of complete evaporation thus the damage caused by localized concentration effects (dissolution of iron forming the soluble, nonprotective, sodium ferroate [sodium hypoferrite] salt, together with hydrogen liberation, tube wastage, and ultimate failure) does not occur. 

Alpha-quartz has many useful properties which lead to its wide use in industry as a glass, ceramic and molecular sieve. However, undoubtedly its most technically important use occurs by virtue of its piezo-electric properties, which allow it to be used as a frequency regulating device in satellites, computers, and the ubiquitous quartz-watch . Unfortunately, it has been found that quartz crystals are susceptible to damage by radiation, and that this is associated with the presence of defects in the crystal lattice. These defects, particularly aluminum and hydrogen, are grown into the crystal and so far have proved impossible to remove. This problem has been the cause of intensive research, which has led to some information on the possible types of defects involved, but has failed to produce details of their geometries, and the way in which they interact. 

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