Nonconductive Objects

Where there could be high surface charging processes, nonconductive materials should not be used, unless the breakdown voltage across the material is less than 4kV. Examples of nonconductive objects include plastic pipes, containers, bags, coatings, and liners. 

Electroforming consists of depositing a metal plate on an object with the purpose of preparing a duplicate of the object in all its detail. Nonconducting objects can be rendered conductive by coating them with a conductive layer. The plated metal forms on a part called a mandrel, which forms a template and from which the new metal part is separated after the operation. The mandrel may be saved and used s ain or dissolved away with chemicals to separate it from the new object. 

If an individual remains in contact with the live circuit, either disconnect the current source, preferably at the circuit panel rather than at the equipment if possible, or remove the victim from contact with the current source. If the victim is immobilized in contact with liquid, do not come into contact with the liquid. Using a nonconductive object such as a plastic rod or dry wooden stick, either move the wires or the victim (Figure 15.4). Remember, only if the circuit cannot be deactivated should you attempt to move the wires or the victim. Perform this operation quickly and safely. 

Density The ratio of the mass of an object to its volume. Depletion layer A nonconductive region in a reverse-biased semiconductor. 

As shown by this reaction, the metallic ions Mz+ will be reduced to metal M, while the reducing agent ions R" will be oxidized to Rz ". In this way, the reduction of metal ions occurs both at the surface of an object at which the deposition can proceed (an appropriate metallic surface or properly activated nonconductive materials, e.g., ceramics, polymers, and textiles) or in bulk solution. 

There are advantages for using the electroless plating process. It does not require electrical power. Metal is deposited evenly along a part s edges and inside holes as well as over irregularly shaped objects. Also the process can deposit a conductive surface on a nonconductive item so that it can be electroplated. 

Samples must be solid and may be in almost any form. Thin films, bulk solids, particles, powders, machined pieces, and small objects (including biological specimens) can be analyzed. AU elements from beryllium (Z = 4) to uranium can be determined at concentrations of about 100 ppm or greater. For qualitative analysis, the surface finish of the sample is not important. For quantitative analysis, the surface of the specimen must be flat. A common method for achieving a flat surface for an SEM sample is to embed the sample in epoxy and then carefully polish the hardened epoxy to expose a flat surface of the sample. Calibration standards should have flat surfaces as well, and the composition of the standards should be similar to that of the samples. Alternatively, an FP approach using pure element standards can be used. For nonconductive samples, a thin coating of osmium is deposited on the surface of the sample. 

Metals and alloys are in principle good materials for SIMS analysis. They are highly electric conductive materials and can easily be handled so as to obtain clean, flat, and smooth analyzable surfaces, and they are also usually ultrahigh-vacuum-friendly. However, archaeological and/or artistic metal objects do not always possess all of these properties due to degradation processes, which may chemically modify the external surface and deep regions of the samples. Nonconductive patinas and infiltrated compounds may often form as a result of long burial in soil or exposure to the atmosphere, and these have very different characteristics compared with those observed for metal materials. 

Nonconductive means that, because of the nature and condition of the materials used, and the conditions of use (including environmental conditions and condition of the material), the object in question has the properly of not becoming energized (that is, it has high dielectric properties offering a high resistance to the passage of current under the conditions of use). 

If contact with a live electrical circuit has taken place, the first step should be to cut off the current at the circuit breaker box. If this is not possible, separate the victim from the electrical source using a nonconductive material such as a lab coat, wooden chair, or rubber hose. Make sure that you do not become involved in the circuit (avoid water spills or making contact with grounded objects such as water faucets or other electrical equipment). If the victim is unconscious, attempt to arouse him or her by gentle shaking. If breathing has stopped or a pulse cannot be felt, apply cardiopulmonary resuscitation (CPR) following approved methods. Send someone to call for medical help. 

The coating operations begin by mixing the active materials, polymer binder and conductive diluent. The objective of the dry blend is to coat the nonconductive particles of the active material with a thin film of the conductive carbon. This coating provides electrical contact to the current collector for full utilization of all the particles in the mix. The polymer is... 

---