Compatibility of materials

To perform due diligence to characterize the waste stream, the facilities engineer may be faced with some challenges such as the following  

Another key aspect to treating CMP waste streams is to ensure that only the wastes assigned to the waste treatment system are sent down the drain. In short, a specific waste drain is not to be used as the general-purpose drain. A drain must be assigned for the collection of a specific CMP waste since the treatment system is designed around the composition of the waste. 

The main drivers for understanding the properties of the waste stream are the definition of the following  

Once the waste stream has been characterized, it is possible to select the proper materials of construction for waste treatment facility. Proper selection will prevent the waste collection and treatment systems from corroding, eroding, and/or falling apart when exposed to the waste stream. When selecting materials for the waste treatment system, one must consider an array of factors such as cost, ease of maintenance, replacement, and chemical compatibility for future potential chemical usage. It is in the best interest of the waste system design engineers, to the best of their ability, to select the proper materials of construction. 

As the industry moves toward more exotic chemistries and oxidizers, there may be a need for higher performance (and significantly more expensive ) fiuoropolymers such as PFA and PVDF. To define the appropriate materials for a specific waste treatment system, it is best to design a series of experiments involving soak tests with samples of the CMP waste with the proposed materials of construction. To ensure proper material selection, data collection during the experimentation should include the following  

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The term PDC is defined as polycrystalline diamond compact. The term TSP is defined as thermally stable polycrystalline diamond. TSP materials are composed of manufactured polycrystalline diamond which has the thermal stability of natural diamond. This is accomplished through the removal of trace impurities and in some cases the filling of lattice structure pore spaces with a material of compatible thermal expansion coefficient. 

The cartridge filter is typically a 5- to 10-micron nominal cutoff filter. The housing can be PVC, FRP, or SS (again, take heed of the materials of compatibility). It should be equipped with a differential pressure gauge to measure the pressure drop across the filter. Cartridge filters should be changed out with every new cleaning solution. 

Liquid toners are suspensions of toner particles in a fluid carrier. The carrier is typically a hydrocarbon. Dielectric, chemical, and mechanical properties of the Hquid must be compatible with the photoreceptor, the suspended toner particles, and the materials of the development equipment. Liquid toners are capable of producing higher resolution than dry toners because of the smaller (3—5 -lm) particle size achievable. Development of the latent image occurs as it passes through a bath of toner and the charged particles are attracted to the oppositely charged surface. 

Pipelines. The feasibility of pipeline transportation depends on the availability of very large quantities of compatible materials between locations with sufficient storage facilities. Thus, pipeline transportation is predominantly, but not exclusively, limited to the movement of hydrocarbons, many of which are raw materials in the production of petrochemicals. Although proprietary pipelines (qv), generally of short distances, ate not unusual, commercial petroleum pipelines are considered to be common carriers available to serve all customers who can tender sufficient quantities of acceptable liquids for transportation between terminals. 

Poly(ethyl methacrylate) (PEMA) yields truly compatible blends with poly(vinyl acetate) up to 20% PEMA concentration (133). Synergistic improvement in material properties was observed. Poly(ethylene oxide) forms compatible homogeneous blends with poly(vinyl acetate) (134). The T of the blends and the crystaUizabiUty of the PEO depend on the composition. The miscibility window of poly(vinyl acetate) and its copolymers with alkyl acrylates can be broadened through the incorporation of acryUc acid as a third component (135). A description of compatible and incompatible blends of poly(vinyl acetate) and other copolymers has been compiled (136). Blends of poly(vinyl acetate) copolymers with urethanes can provide improved heat resistance to the product providing reduced creep rates in adhesives used for vinyl laminating (137). 

Corrosion Inhibition. Another important property of antifreeze solutions is the corrosion protection they provide. Most cooling systems contain varied materials of constmction including multiple metals, elastomeric materials, and rigid polymeric materials. The antifreeze chosen must contain corrosion inhibitors that are compatible with all the materials in a system. Additionally, the fluid and its corrosion inhibitor package must be suitable for the operating temperatures and conditions of the system. 

Future brakes must satisfy health standards and most vehicle manufacturers have moved toward removing all asbestos from brakes. Lighter weight rotors and caUpers based on aluminum-based metal-matrix materials are also on the horizon for lighter vehicles requiring a whole new family of compatible friction materials. 

Other Uses. As a biocide, chlorine dioxide is more effective than chlorine over a wider pH range. Chlorine dioxide is also less corrosive and more compatible with some materials of constmction. Chlorine dioxide has a wide variety of small appHcations in drinking water, food processing (qv), cooling towers, and oil recovery. In these areas, chlorite is the preferred source of chlorine dioxide. 

There are, however, numerous appHcations forthcoming ia medium- to small-scale processiag. Especially attractive on this scale is the pharmaceutical fine chemical or high value added chemical synthesis (see Fine chemicals). In these processes multistep reactions are common, and an electroorganic reaction step can aid ia process simplification. Off the shelf lab electrochemical cells, which have scaled-up versions, are also available. The materials of constmction for these cells are compatible with most organic chemicals. 

Polymers used for seat and plug seals and internal static seals include PTFE (polytetrafluoroeth ene) and other fluorocarbons, polyethylene, nylon, polyether-ether-ketone, and acetal. Fluorocarbons are often carbon or glass-filled to improve mechanical properties and heat resistance. Temperature and chemical compatibility with the process fluid are the key selec tion criteria. Polymer-lined bearings and guides are used to decrease fric tion, which lessens dead band and reduces actuator force requirements. See Sec. 28, Materials of Construction, for properties. 

The selection of materials of construction for rotaiy pumps is critical. The materials must be corrosion-resistant, compatible when one part is running against another, and capable of some abrasion resistance. 

Thermal conductivity of these materials is veiy low and affec ts the overall coefficient. When several materials are compatible, explore all of them, as final cost is not always the same as raw material costs. 

These include glass, sihcon carbide, and similar variations. Even larger tubes are available in these materials, up to 19-mm diameter. They have high thermal conduc tivities and are usually very smooth surfaces to resist fouhng. Very high material/fluid compatibility is seen for these products, not many fluids are excluded. Brittleness is a consideration of these materials and a complete discussion of the service with an experienced suppher is warranted. The major selection criteria to explore is the use of O rings and other associated joints at tubesheet. The shell is steel in most cases. 

Corrosive chemicals and external exposure can cause tank failure. Materials of construction should be chosen so that they are compatible with the chemicals and exposure involved. Welding reduces the corrosion resistance of many alloys, leading to localized attack at the heat-affected zones. This may be prevented by the use of the proper alloys and weld materials, in some cases combined with annealing heat treatment. 

Inappropriate Select compatible materials of construction for materials of con- the specific process struction lead to, Change process parameters (e.g., different acid, corrosion and reduce temperature). Evaluate changes with test potential failure. coupons off-line Dillon 1992... 

Standard materials for the compressor are cast iron for the cylinder and carbon steel for the shaft. The rotor parts are steel. The liquid pistf f compressor has another feature that compensates for low efficiency, using special materials of construction and compatible liquid compr sant, unusual or difficult gases may be compressed. By using titanium internal materials and water as a compressant, gases containing wet chlorine can be compressed. This is a very difficult application for most o( the other compressor types. 

A chemical will be a solvent for another material if the molecules of the two materials are compatible, i.e. they can co-exist on the molecular scale and there is no tendency to separate. This statement does not indicate the speed at which solution may take place since this will depend on additional considerations such as the molecular size of the potential solvent and the temperature. Molecules of two different species will be able to co-exist if the force of attraction between different molecules is not less than the forces of attraction between two like molecules of either species. If the average force of attraction between dissimilar molecules A and B is and that between similar molecules of type B Fbb and between similar molecules of type A F a then for compatibility Fab - bb and AB - P/KA- This is shown schematically in Figure 5.5 (a). 

Selection of materials of construction compatible with the chemical(s) in use, properly cleaned and passivated... 

Cas Hazard Materials of construction for ancillary services Compatible Incompatible... 

Are materials of construction compatible mutually and with process materials ... 

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