Tinning Flux

Tinning is the process of applying a protective coating of tin to another metal. Flux is a material that is used to lower the melting temperature of the materials or to aid in their fusion in this and related soldering processes. Zinc chloride is a common tinning flux. 

Depending on temperature and pressure, all materials in the solid and liquid state have a vapour pressure, that is, some of their surface atoms or molecules exist as a vapour or gas above the material. Thus under certain conditions a liquid evaporates and some solids sublimate. This is most familiar to us as we smell coffee or perfumes the fragrant molecules leave the liquid and enter the surrounding atmosphere. Mothballs are an example of the tendency of solids, like naphthalene, to enter the gaseous state. Volatility is the meas- 

Volatility refers to the relative rate of evaporation of materials to assume the vapor state. US 171.8 

Many substances will react with the moisture or oxygen (or other gases) in the air. As a consequence, they may be wetted covered with water, alcohol, oil, or other material that separates the reactive substance from the atmosphere. The dilution afforded by this process may also serve to desensitize the mixture. Wetting agents are sometimes added to water to reduce its surface tension and help it spread and penetrate the substance. Many explosives are desensitized by being wetted. See Terminology, Desensitized, p.234. 

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A number of binary phosphides and polyphosphides (compounds containing P—P bonds), for instance those of Mn, Tc, Re, Fe, Ru, Os can be prepared, often in well crystallized form, by the tin-flux technique. The mixture generally containing an excess of P (red P) and a high excess of tin is heated, possibly at a slow rate, to the required temperature (600°-1000°C) and maintained at that temperature for several days and then slowly cooled. In several cases the products may be recovered by dissolving the tin-rich residue in hydrochloric acid. The preparation of several ternary phosphides and of arsenides and antimonides has also been described (see 6.11.3). 

In the review by Kanatzidis et al. (2005), the preparation by the tin-flux method is mentioned also for several ternary phosphides and polyphosphides of rare-earth and transition metals. Typically the components (R metal, T metal, P and Sn in an atomic ratio of about 1 4 20 50) in sealed silica tubes were slowly heated, to avoid violent reactions, up to 800°C, annealed at that temperature for 1 week and slowly (2 K/h) cooled to ambient temperature. The tin-rich matrix was dissolved in diluted hydrochloric acid. The authors described the preparation of compounds corresponding for instance to the formula MeT4P12 (Me = heavy rare-earth metals and Th and U, T = Fe, Ru, etc.) and to the series of phases MeT2P2 (Me is a lanthanide or an actinide and T a late transition metal) having a structure related to the BaAl4 or ThCr2Si2 types. 

The overall data may not be used in such an absolute sense as in analysis of a bronze casting, but they do provide some interesting information. Substantial concentrations of gold and arsenic were observed that appear to correlate with one another and with antimony concentration. Further work is needed to find authentic sources of the copper, tin, fluxes, and other materials used at these sites. Apparently, measurement of gold concentrations cannot be used to answer questions about a change in the sources of tin during this period. 

Rhenium phosphides with Re-Re bonds (e.g., Re2Ps ResP, ReP, ResPia ) are formed in high temperature reactions of Re metal and red P. Use of the tin flux technique proves advantageous L... 

TINNING FLUX (7646-85-7) Reacts with water, forming an acidic solution (pH about 4) zinc oxychloride may be formed with large amounts of water. Violent reaction with strong bases, potassium. Attacks metals as fume or in the presence of moisture. 

Several phosphides of technetium were prepared by reaction of technetium metal powder with red phosphorus at 1220 K using the tin-flux technique or iodine as a mineralizer. The preparation was carried out in evacuated, sealed silica tubes. 

This invariance is invoked in the transformation between the laboratory and tiie c.m. system. The invariance of the velocity-space distribution to a change in coordinate system is also one of the arguments for the use of tins flux map in Section 6.4. 

Methods of preparation (1) ampoule synthesis from the pure components (2) melting in arc furnace (3) tin flux method (4) other method. 

Babizhets ky and Kuz ma (1994) constructed the phase diagram of the Ce-Ni-P system at 1070 K (the range with Ce content of 0-33 at.%) and 870 K (the rest of the system) (fig. 23). The compounds CeNi5 (P3 and CegNiePn were not found at the temperatures investigated a single crystal of the former compound was extracted from an arc-melted sample. The latter was synthesized by the tin flux technique. 

Some of the reported phosphorus-rich metal phosphides have been synthesised from the elements (powdered metal and red phosphorus) at elevated temperatures (700-1,200 °C), or at moderate temperatures for extended periods of time in tin fluxes (up to 550 °C, more than 10 days) [110, 127, 130-132]. These species can also be prepared by heating the elements in the presence of a chemical transport agent such as CI2 or I2 in sealed ampoules (between 600 and 800 °C)... 

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