Nonconductors

As expected from the enthalpy of formation, water is thermally very stable but when steam is heated to above 1300 K slight dissociation to the elements does occur. Pure water is almost a nonconductor of electricity but slight ionic dissociation occurs ... 

Lead azide is not readily dead-pressed, ie, pressed to a point where it can no longer be initiated. However, this condition is somewhat dependent on the output of the mixture used to ignite the lead azide and the degree of confinement of the system. Because lead azide is a nonconductor, it may be mixed with flaked graphite to form a conductive mix for use in low energy electric detonators. A number of different types of lead azide have been prepared to improve its handling characteristics and performance and to decrease sensitivity. In addition to the dextrinated lead azide commonly used in the United States, service lead azide, which contains a minimum of 97% lead azide and no protective colloid, is used in the United Kingdom. Other varieties include colloidal lead azide (3—4 pm), poly(vinyl alcohol)-coated lead azide, and British RE) 1333 and RE) 1343 lead azide which is precipitated in the presence of carboxymethyl cellulose (88—92). 

A primary advantage of electroless solutions is the abUity to produce conductive metallic films on properly prepared nonconductors, along with the abUity to uniformly coat any platable object. The most complex geometric shapes receive a uniform plated film. Film thicknesses range from <0.1 /tm, where only conductivity or reflectivity is wanted, to >1 mm for functional appHcations. 

Plating on nonconductors comprises two technologically very different categories plating of plastics and priated circuit productioa. 

Most priated circuit board (PCB) production uses the subtractive process (41). In the simplest version, a thin copper foil is laminated to a nonconductor, holes are fabricated, and the unwanted copper etched off. These siagle-sided boards do not require plating. Known as ptint-and-etch, this version is used for the most simple priated circuit boards. 

An alternating-current electrode svstern referred to in the indiisti v as a wiper is often installed in the nonconductor product-collection section behind each drum. The function of the wiper is to use an ac corona to neutralize the charge on the nonconductor particles pinned... 

The double layer can be formed by contact (triboelectric) charging of one surface of the nonconductor, while the opposite surface is in contact with a conductor, e.g., a nonconductive coating on a metal chute or a plastic-lined, metalpipe for powders. A less frequent cause is contact-charging of one surface, while air ions are supplied to the opposite surface. 

Conductive objects may accumulate charge via conduction, induction, ion collection or contact-separation in relation to a nonconductor. In general, charge accumulation on conductive objects can be completely prevented by bonding and grounding. The only decisions to be made are how small the resistance to ground must be (4-1.3) and how small a conductive object needs to be before it can be neglected. The latter depends on the results of... 

A particular problem is determination of surface charge density on a nonconductor which has charges of opposite polarity on either side (bipolar... 

The surface potential on a plane nonconductor, such as a charged web or belt, can be measured using normal field meter techniques. The readings are very useful for comparative purposes but are not... 

Real-space three-dimensional imaging in air, vacuum, or solution with unsurpassed resolution high-resolution profilometry imaging of nonconductors (SFM). 

Nonconductors of electricity when pure. Molecules are uncharged, so they cannot carry an electric current. In most cases (e.g., iodine, I2, and ethyl alcohol, C2H5OH), water solutions of molecular substances are also nonconductors. A few polar molecules, including HC1, react with water to form ions ... 

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