Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/02—Coating starting from inorganic powder by application of pressure only
  • C23C24/04—Impact or kinetic deposition of particles

Definitions

• Nails are manufactured in a wide variety of sizes. There are stilt 60d spikes, long narrow box nails, large-headed roofing nails, small tacks, and then a wide variety of special nails, such as twisted Ardox nails, grooved nails, and so on. Nails are handled in large volume, and the plating barrel to handle commercial loads may range in size from 3 feet to 5 feet in diameter, for example. A 5-foot diameter barrel may carry a load of two tons of nails. The operation may work admirably with small roofing nails, for example, but not when the charge is switched to 16d box (these are long, very thin nails which bend very easily). It is known that there are active and relatively inactive zones in a tumbling barrel.
• the nails do not ride separately, but tend to revolve in a tumbled mass. This condition results in a rough and uneven plating and may result in bare areas under the heads of the nails. Now it is true that 60d nails or 16d box nails, for example may constitute only a small portion of the production of a large nail mill; nevertheless, the manufacturer would desire to have all of his nails coated by a single process and not have to maintain two separate operations to coat his nails.
• Chains also come in a wide variety of shapes and sizes. Dealing with massive proof-coil chain, glass beads (which are normal impact material) are caught between the hammer and anvil action of one chain link striking another, and the glass beads can be ground to glass powder.
• a wide variety of chain sold industrially is called woven chain, and is made from wire which is bent on the links. These links constitute a widely diverse condition of shielded shapes.
• a good example of shielded areas in chains is the sash chain. This is made of small, fiat strips of metal bent over to form individual links. The interior surfaces of these links are extremely difficult to reach with any effective impact material. They are, moveover, so small that it is very difficult to generate energy to compact the coating onto the interior surfaces.
• a chain manufacturer may also manufacture, for example, snaps such as the snap on the end of a chain used for holding dogs. Obviously, the tumbling characteristics of long lengths of chain are entirely different from the ordinary dog snap.
• Such a snap itself is an example of various steels, including spring steel, and has various shielded areas. Once again, it is not enough to be able to plate percent of such a manufacturers products. It is very desirable to plate percent.
• Bolts for example, come in a variety of sizes from very large to very small, and they may have a wide variety of head shapes. Philipshead bolts, for example, have a starshaped hole in the head of the bolt. This area must be plated completely for satisfactory commercial results. Similarly, with wood screws there is a rectangular slot for the screwdriver on the head of the screw and this must also be plated. On large bolts the threads may be fairly open and easy to reach, but on very small bolts or fine threads it is extremely difficult to penetrate to the root of the thread and deposit a uniform coating all around the thread. It may be coated with zinc, but usually the deposit in such areas is not as well consolidated as it is on more readily accessible surfaces.
• stampings may, for example, be in the shape of small boxes. These boxes may fill up with impact medium and material during the tumbling operation and little or no plating will occur on the inside of the box.
• the list of problem articles could be greatly expanded but the foregoing will serve to illustrate the nature of the problems of the mechanical plater.
• plating metal for instance zinc
• the available supply of metal can be readily deposited on the exposed surfaces, leaving little or none for the plating process to occur in the recesses because it is so slow.
• a much more practical impact medium for use with zinc plating metal consists of pie-shaped glass fragments or irregular pieces of glass. These may be very successful in plating the recessed areas, but their use can introduce major problems in the plating of articles.
• the principal problem from irregular or pie-shaped pieces of glass or other material used as impact media is lodgment of the irregular pieces in the work being plated. It is very difficult to insure that no lodgment will occur. For example, in Philipshead bolts it is disastrous to have any pieces of impact material caught in the recessed head, because it will not be possible to insert a screw driver.
• Lodgment is not the only problem associated with the use of large or irregularly shaped impact material. 'It may very easily happen that the work to be plated is smaller than the irregular impact material. This creates problems in separating the impact material from the plated work, and in some cases magnetic separation is the only possible way of accomplishing the job economically.
• 'A very much more desirable type of impact material consists of very fine glass beads, which have no lodgment problem and which can be pumped by a-sand pump like water. This provides a very convenient .and handy way of handling the impact medium in large industrial plants.
• the impact medium may be discharged by gravity from the plating barrels and after separation of the plated work, the fine beads and water can be picked up by the pump and pumped into an overhead tank where it can be returned by gravity to the barrels.
• large or irregularly shaped impact material would not lend itself to the pumping technique and usually cannot be used at all.
• the preferred lubricious and aromatic additives of low viscosity vary widely in chemical nature and it is believed that any water-insoluble, aromatic compound having relatively low viscosity and relatively high boiling point yet relatively volatile is operable.
• the preferred materials may be classified chemically in various manners.
• One preferred class materials is made up of oxygencontaining compounds including aromatic ethers, esters, alcohols, aldehydes, ketones.
• a preferred class may also be defined as substituted benzenes having at least the substitution indicated by the following structural formula:
• R is an organic radical having the formula:
• R is an organic radical and wherein x is an integer of from 0 to 8,
• Anisole (methylphenyl ether) Safrole (methylene ether of allyldioxybenzene) Aubepine (anisic aldehyde) Heliotropine (piperonyl aldehyde) Dihydro safrole Acetanisole (paramethoxy acetophenone) Acetophenone (methyl phenyl ketone) Propiophenone Methoxproiophenone Dimethyl acetophenone Giv Tan f (2 ethoxyethyl p-methoxy cinnamate)
• the preferred materials mentioned have characteristic groups substituted directly in benezene ring. These preferred groups are alkoxy, alkylene dioxy, and carbonyl linking either hydrogen, alkyl or phenyl radicals.
• aubepine While all of the above listed compounds are especially effective in the practice of the invention to give smooth coatings and reach recesses they are not all useful to the same extent, for the same purposes.
• materials containing the CH0 grouping such as aubepine produce particularly smooth zinc coatings, but they are not particularly bright or shiny.
• the use of aubepine has a tendency to result in a film of metal such as zinc over the sides of a rubber lined plating barrel and this detracts substantially from the plating efiiciency by removing zinc intended for the work being plated and depositing it on the barrel.
• aubepine is not particularly recommended for zinc or cadmium plating, but it is particularly useful in plating brass or copper, particularly if it is desired to plate using glass beads as impact material. Under the same conditions much heavier brass or copper coatings can be deposited when using aubepine in the plating operation than can be obtained when it is omitted.
• Particularly suitable for zinc and cadmium deposition are the aromatic ketones, such as acetophenone and propiophenone. These materials produce smooth, bright coatings and there is no trace of zinc build-up on the sides of the barrel, and the plating efficiencies are very high.
• phthalates have a great deal of usefulness in the practice of this invention. These materials are absolutely odor free, and are extremely inexpensive. Diethyl phthalate, for example, can be bought for about 22 cents per pound. The use of the phthalates produces very lustrous and exceptionally smooth coatings. The penetration is excellent and extremely recessed, and normally impossible areas to plate are covered effectively with a well consolidated coating. These phthalates are also useful in the plating of brass, copper and other hard to plate metals, and their use, results in enhanced depth of deposit. These phthalates, however, are not particularly evaporative, and are somewhat oily in their characteristics, particularly the higher members of the series.
• dimethyl phthalate di(n-butyl) phthalate
• diisodecyl phthalate diethyl hexyl phthalate
• dicapryl phthalate dimethyl phthalate
• the higher members of this series have very high boiling points, are quite oily, and have low vapor pressures. I find that their use tends to deposit a film of readily weldable metals, such as zinc, on the rubber surfaces of a rubber-lined tumbling barrel. This, as noted above, results in a loss of zinc to the charge and substantially lower zinc efficiencies which cannot normally be tolerated except in special circumstances. This difliculty of coating the barrel sides does not apply to brass, copper and other hard to plate metals having higher melting points and recrystallization temperatures.
• fatty acid esters particularly those of the short carbon chains, such as butyl acetate. While butyl acetate is particularly effective it has a strong, fruity odor. It is very evaporative, and will correct the tendency of some materials to leave films on the barrel sides, but it tends to be two odoriferous to use in nonvented locations. Slightly higher esters are particularly effective, for example, isobutylcaproate. A combination of isobutylcaproate and safrole, for example, has resulted in some of the smoothest and shiniest coatings.
• solvents for these primary additives can be selected from among unsaturated fatty alcohols such as oleyl alcohol.
• Another particularly useful class of solvents is the glycols, for example, triethylene glycol. This is not only an excellent solvent but it is also water soluble, and will readily dissolve the phthalates described as above. When diluted with triethylene glycol, these phthalates are much improved in their performance.
• cresols particularly the methylated and propylated cresols such as carvacrol.
• an'additive may contain an aromatic ketone, a fatty acid ester, a silicone defoaming agent, and xylol or some other suitable solvent which is used as an over-all solubili-zer or carrier or extender.
• these agents are all mutually soluble one in another, so it is not necessary to work with emulsions, although emulsions can be formulated which work very well.
• the reagents are solids such as heliotropine, they may readily be dissolved in some other aldehyde such as aubepine.
• the substantial dilution of such reagents as dimethylphthalate in such solvents as Xylol, toluol triethylene glycol and the like make it possible to largely overcome the previously discussed defect of depositing metal on the sides of the barrel.
• these diluents or solvents are traditionally inexpensive so that a relatively substantial amount can be used without adding to the cost of the mix. Some care has to be exercised in the selection of the diluent if large quantities are to be used, so as not to interfere with the plating operation.
• Example No. 5 Purely for the purposes of comparison with Example No. 5, the run was repeated exactly, except that 4 cc. of acetophenone were substituted for the 2 cc. of acetophenone and 2 of isobutylcaproate used in Example No. 5. All other conditions remained exactly the same. The results from this run were very good. The coating was very smooth, a good bright color, the brightness was excellent. The penetration was very good, but it was easily able to differentiate between the two results when they were compared side by side. The results from Example No. 5 were definitely smoother and better than those from Example 6, good as those were.
• A-l8 springwire hose clamps as used previously were abrasively cleaned and coppered as described above. They were placed in a mill a described, with grams of zinc dust, and the additive consisted of 2 cc. of diethylphathalate, 1 cc. of acetophenone, 12 drops of a Dow Company silicone agent #200. The activator and other conditions were the same as described at the beginning of the examples, and were run for one and one-half hours. At the expiration of this time, the clamps were found to have an absolutely brilliant polish, they were relatively very smooth, there was absolutely no foam, and no odor on opening. It was possible to look through the clear liquid and see the clamps lying in the beads. The zinc etficiency was good but there was a thin skin of zinc on the barrel lining.
• Example No. 8 was repeated exactly, except that 3 cc. of diethylphthalate were used. On opening the barrel, brightness, smoothness, and penetration were good, but the eificiency was considerably reduced, and there was a heavy smear of zinc on the barrel sides. The clamps were not as brightly polished as in Example No. 8.
• safrole Three hundred parts by weight of safrole were added to 250 parts by weight of butylacetate, and 50 parts by weight of acetophenone. These ingredients were thoroughly mixed together, and a portion of this mix was used in a number of tests.
• a tumbling barrel approximately 5 feet long, inches in diameter and divided into two compartments, each compartment capable of processing between 500 to 600 pounds of hose clamps, was used for this example.
• a number of different runs were made using different sizes of spring wire hose clamps, similar to those used in the preceding examples.
• the amounts of zinc used varied according to the size of the clamps. Approximately 550 pounds of clamps were used in each test.
• the promoter activator consisting of a flux and surface active agent
• tin bumps When articles are plated in the absence of the additives, coatings of tin metal are usually or very frequently characterized by the presence on the coating of small bumps. These are frequently referred to as tin bumps. They are believed to be caused by the rapid build-up of the coating caused by the easy platability of tin. It may be that some particles of the tin plate together before they are impacted to the coating and are thus responsible for the presence of these small, inconspicuous, but none theless unattractive, tin bumps. The use of acetanisole and safrole in combination entirely eliminated the presence of tin bumps, and the coating was remarkably smooth and uniform.
• Example 14 was repeated, except that one and one-half pounds of sash chain was substituted for the woven. wire chain.
• the chain was found to be completely coated with zinc, including the recessed areas on the inner surfaces of the sash chain. This. type ofrecess is very small and hard to get into, and for the most part is very difficult to plate using conventional means.
• the invention resides in the use of certain aromatic organic additives which have been found to improve the mechanical plating processes described by providing greater penetration. While a broad class of water-insoluble aromatic organic additives is described, the most useful materials appear to be non-acidic, lubricious, high boiling, volatile or non-persistent and of low viscosity, By lubricious” is meant non-sticky. Water insoluble is used in its accepted sense as including very slightly soluble materials.
• volatile as used herein is intended to mean non-persistent. That is, the materials will have measurable vapor pressure at relatively low temperature. Preferred materials have a vapor pressure of at least 5 or 10 mm. Hg at 100 F., although less volatile materials can be used.
• low viscosity as used herein is intended to mean, light, free-flowing materials as opposed to heavy or waxy materials.
• the viscosity of the preferred ma-. terials is generally below 50 or 100 cps. at temperatures of up to about 100 F. although more viscous materials may be used. Still more preferably, the viscosity of the materials is below about 20 cps. at room temperature.
• the present additive can be used in very small amounts but very large amounts do not cause any difficulty. Accordingly, there does not appear to be any requirement to limit the amount of additive to any minimum or maximum values .as some improvement in penetration and smoothness is obtained with minuscule additions. As mentioned, as little as 1 gram of additive to 6 pounds of work, or 0.05% by weight, additive has been found quite effective. In general, however, it can be said that for a normal charge of from l00parts to 2500 parts of work, from 0.1 part to 50 or 100 parts of the water insoluble additive can be effectively used. On this basis, the amount of additive could vary from 0.005 to 100 wt. percent, based on the amount of work to be plated.
• a charge would ordinarily include from 5 to 300 parts of metal plating particles, from 500 to 3000 parts of water, and from 5 to 200 parts of promoter which itself is conveniently water, 10% filming agent and 25% flux.
• the impact media if not the object to be plated, can be used in amounts of from 400 to 3000 parts. Accordingly, the amount of additive used according to the invention can be based on the work, or on the charge, or any of the components.
• a water-insoluble oxygen-substituted lubricious aromatic organic compound additive is provided in said medium to improve said plating process, said additive being present in an amount of from 0.005 to 100 percent, by weight, based on the weight of said metallic particles and having a vapor pressure of at least mm. Hg at 100 F. and a viscosity of less than 100 cps. at 100 F.
• R is an organic radical having the formula:
• x is an integer of from 0 to 8
• R is an organic radical and wherein x is an integer of from 0 to 8,
• R is an organic radical and .wherem x 18 an integer of from 0 to 8; wherein R is either an organic radical or hydrogen; and
• R and R may together form a cyclic ether radical having the following structural formula:
• An improved method according to claim 1 wherein the additive comprises at least one compound selected from the group consisting of aromatic ethers, aromatic ketones, aromatic aldehydes, aromatic esters, and aromatic alcohols.
• ether is selected from the group consisting of anisole, safrole, isosafrole, dihydros-afrole, aubepine, heliotropine, acetanisole, methoxypropiophenone, 2 ethoxyethyl p-methoxy cinnamate and mixtures thereof.
• aromatic ketone is selected from the group consisting of acetophenone, dimethylacetophenone, propiophenone, benzophenone, and mixtures thereof.
• ester is selected from the group consisting of diethyl phthalate, dimethyl phthalate, di (n-butyl) phthalate, diis'odecyl phthalate, diethyl hexyl phthalate, dicapryl phthalate and mixtures thereof.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemically Coating (AREA)
• Paints Or Removers (AREA)

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Citations (8)

• 1966
  • 1966-07-22 US US567087A patent/US3479209A/en not_active Expired - Lifetime
• 1967
  • 1967-07-20 DE DE1967C0042916 patent/DE1621219B2/de active Granted
  • 1967-07-21 GB GB33631/67A patent/GB1184098A/en not_active Expired

Patent Citations (8)

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