Silicon poisoning

Poisoning of Pellistor by, e.g., silicones, halocarbons, leaded petrol Too high a sampling rate (causing cooling of the elements)... 

To retard corrosion and to facilitate future maintenance (e.g., allow the non-destructive removal of threaded Junction box covers), all threaded connections should be lubricated with an antiseize compound which will not dry out in the environment. If lubricant is applied to the threaded (or flanged) portion of covers of explosion-proof enclosures, the lubricant must have been tested and approved as suitable for flame path use. It is cautioned that some lubricants contain silicone, which will poison most catalytic gas detector sensors and should not be used near gas detectors. 

Recochem hic., hiternational Division, 149 Regional Center for Poison Control and Prevention Serving Massachusetts and Rhode Island, 314, 317 Regional Poison Control Center, 311 REGLONE , diquat bromide, 114 Rebels Inc., 230, 245 Reiclihold, 182 Reilly Industries Inc., 245 Reliance hidustries Ltd., 175 Reliance Silicones (hidia) Ltd. (RSIL), 175 Repsol YPF SA, 203... 

Ferrosilicon containing 30-75% of silicon is hazardous, particularly when finely divided, and must be kept in a moisture-tight drum. In contact with water, the impurities present (arsenide, carbide, phosphide) evolve extremely poisonous arsine, combustible acetylene and spontaneously flammable phosphine [1 2],... 

The lifetime of metal oxide gas sensors in general is several years. Nevertheless poisoning effects can occur when exposed to silicones. An example of commercial Ga203-semiconductor gas sensors is shown in Fig. 5.32. 

Antimony (Sb), 3 41-56, 56. See also Group Ill-Sb system InAsSb alloy InSb photodiode detectors/arrays Lead-antimony alloys Low antimony lead alloys Stib- entries in babbitts, 24 797 catalyst poison, 5 257t chemical reactions, 3 42—44 in coal, 6 718 economic aspects, 3 47-48 effect of micro additions on silicon particles in Al-Si alloys, 2 311-312 effect on copper resistivity, 7 676t environmental concerns, 3 50 gallium compounds with, 12 360 health and safety factors, 3 51 in pewter, 24 798... 

The other chemicals mentioned in this book are less dangerous and safety goggles and rubber gloves, which should always be used, are usually sufficient protection. Elementary silicon is inert and shows no toxic effects. In this respect, silicon is different from many other semiconductors, which may contain poisonous compounds. However, sufficient eye protection is required while cleaving wafers, because of the risk of fragmentation. 

Phosphoric Acid Fuel Cell (PAFC) Phosphoric acid concentrated to 100% is used for the electrolyte in this fuel cell, which operates at 150 to 220°C. At lower temperatures, phosphoric acid is a poor ionic conductor, and CO poisoning of the Pt electrocatalyst in the anode becomes severe. The relative stability of concentrated phosphoric acid is high compared to other common acids consequently the PAFC is capable of operating at the high end of the acid temperature range (100 to 220°C). In addition, the use of concentrated acid (100%) minimizes the water vapor pressure so water management in the cell is not difficult. The matrix universally used to retain the acid is silicon carbide (1), and the electrocatalyst in both the anode and cathode is Pt. 

The CPA or "Snake Pen" consists of a pen body containing a porous wick, such as that used in felt pens, and a solution ofDMSO and any number of toxins. When the wick is touched to the victim s skin he receives a fatal dose of poison. The CPA is built from a correction fluid pen, available at any office supply store. These pens have a soft, flexible body and are easy to modify. Unscrew the top from the son pen body, squeeze out the correction fluid and flush the interior with solvent to remove all traces of its original contents. Note that most of these pens have a left-hand thread on the body. The tip of the pen is sawed off and the valve stem carefully removed. Ream out the pen tip to fit the wick. A felt tip marker pen works well as a wick, after being soaked and rinsed in sol vent to remove traces of ink. It may be necessary to trim the wick to fit. Press the wick into the pen tip until about 3/8 " protrudes and seal around it with silicone sealer. When the sealant is dry, put on rubber gloves and, using a hypodermic syringes, inject the DMSO solution into the pen barrel until it is about 3/ 4 full. Be sure not to squeeze the pen while accomplishing this. Coat the barrel threads with a little silicone sealer, screw on the cap and allow the pen to dry in a vertical position. Line the inside of the cap... 

Moissan reasoned that if he were trying to liberate chlorine he would not choose a stable solid like sodium chloride, but a volatile compound like hydrochloric acid or phosphorus pentachloride. His preliminary experiments with silicon fluoride convinced him that this was a very stable compound, and that, if he should ever succeed in isolating fluorine, it would unite with silicon with incandescence, and that therefore he might use silicon in testing for the new halogen. After many unsuccessful attempts to electrolyze phosphorus trifluoride and arsenic trifluoride, and after four interruptions caused by serious poisoning, he finally obtained powdered arsenic at the cathode and some gas bubbles at the anode. However, before these fluorine bubbles could reach the surface, they were absorbed by the arsenic trifluoride to form pentafluoride (18, 23). 

It should be mentioned that most authorities (17) consider the solid solubility of silicon in nickel to be several per cent in the temperature region of this study. The present sample contained only 0.3 per cent Si. This would indicate that a temperature-dependent fraction of the total finds it more economical, from the free energy standpoint, to occur as a surface phase. It may be that certain types of catalyst poisoning consist of the formation of surface phases of this kind on normally active regions of the catalyst. 

Silicon tetrafluoride, fluorosilicic acid, and barium and disodium hexafluorosilicate are poisonous. In mice, the oral LD50 value for disodium hexafluorosilicate is 61 mg kg-. 6... 

Arsenic does not combine directly with carbon, silicon or boron. The reaction with metals to form definite arsenides or alloys is described no pp. 57-78. The presence of small quantities of arsenic or of its compounds in certain catalysts has a poisoning effect. The first traces added to the catalyst have the greatest effect thus the activity of 0-35 g. of platinum was reduced linearly by the addition of arsenic up to 0-7 mg., this quantity reducing the catalytic activity to 45 per cent, of its original value the addition of 10 mg. of arsenic, however, depressed the activity only to 26 per cent, of the original value.3 Vanadium catalysts are poisoned by the presence of arsenic, although the action is slow arsenic pentoxide is formed.4... 

Particulate Matter Other Than Systemic Poisons. Silica and asbestos dust produce fibrosis. Silicon carbide, carbon (other than exhaust emissions), and emery are inert dusts. Many organic dusts, eg, pollen, wood, and resins, cause allergic reactions. Acids, alkalies, fluorides, and chromates are irritants. 

Today the toxic effect of silatranes has been thoroughly studied1-3,16-44a b The toxicity of silatranes varies greatly and is mainly dependent on the nature of substituents at the silicon atom. Most toxic of all known silatranes are 1-arylsila-tranes, 4-XC6H4Si(OCH2CH2)3N, where X = CH3, Cl, H (Table 1). These compounds are almost twice as toxic as such well-known poisons as strychnine and hydrocyanic acid. They produce an intensive stimulation of the motor and respiratory centres1-3,30-34,44,when administered at lower than lethal doses... 

Lewis and coworkers have also made significant contributions to the understanding of the MCS reaction via the use of surface studies72. XPS and AES analysis of catalytically active surfaces showed that zinc causes a restructuring of the Cu3Si surface. Additionally, zinc enrichment is enhanced by the addition of SnCLt. Lead is a well known poison for the direct reaction and the Lewis group found that lead suppressed enrichment of the Cu3Si surface in zinc and silicon. 

In some cases, the reaction of silicon and methanol has been optimized for formation of (MeO)4Si. As discussed above, thiophene addition favored formation of (MeO SiH. Both thiophene and propyl chloride poison copper copper poisoning seems to favor formation of the trialkoxysilane. High-temperature pretreatment disfavors trialkoxysilane formation copper is formed on the surface of the silicon during pretreatment at 450 °C98. Metallic Cu catalyzes dehydrogenation of alcohols and favors formation of (RO)4Si. Workers from Tonen Corporation reported 50% conversion of silicon to make (MeO Si with 92% selectivity if silicon, methanol and Cu(OMe)2 were pretreated (lower conversion and selectivity without pretreatment) and then reacted at 180 °C and 1 atmosphere99. 

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