US20050167005A1 - Pretreatment of aluminum surfaces - Google Patents

Pretreatment of aluminum surfaces Download PDF

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Publication number
US20050167005A1
US20050167005A1 US10/768,825 US76882504A US2005167005A1 US 20050167005 A1 US20050167005 A1 US 20050167005A1 US 76882504 A US76882504 A US 76882504A US 2005167005 A1 US2005167005 A1 US 2005167005A1
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aluminum
deionized water
water
parts
immersion
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US10/768,825
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Michael Barnard
Douglas Hagen
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STAR FINISHES Inc
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STAR FINISHES Inc
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Priority to US10/768,825 priority Critical patent/US20050167005A1/en
Assigned to STAR FINISHES, INC. reassignment STAR FINISHES, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HAGEN, DOUGLAS W., BARNARD, MICHAEL D.
Publication of US20050167005A1 publication Critical patent/US20050167005A1/en
Priority to US11/999,368 priority patent/US20080087357A1/en
Abandoned legal-status Critical Current

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    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • C23C22/66—Treatment of aluminium or alloys based thereon
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process

Definitions

  • the invention is directed to a process for preparing the surface of aluminum to receive colored coatings. More particularly it is directed to a substantially pollution free, non-chromate pretreatment and aluminum conversion coating process which provides improved coating quality, increased process stability and extended operating life of the processing baths.
  • Representative of such systems is the use of SanChem CC3400, a KMnO 4 based compound which is chromium, cyanide and fluoride free.
  • a typical SanChem treatment composition comprises immersion of the aluminum product in a 10% solution of SanChem CC3400+1.7 oz activator @ 135-140° F. for 1.5-2 min to produce a gold color on the aluminum; longer time provides a thicker coating with a darker yellow color.
  • a preliminary step is cleaning the surface prior to the permanganate dips. If an alkaline cleaner is used it is usually followed by a deoxidizer or a mild, nitric acid based solution.
  • the SanChem process comprises degreasing, an alkaline wash at 160° F. (such as SanChem 500,—a mildly alkaline phosphate cleaner), deoxidizing at 125° F. using SanChem 1000 which is a nitric acid based deoxidizer free of fluorides, chromates and heavy metals, forming an oxide film by immersion in DI Water @ 210° F. and a three step sealing process (SanChem 2000+SanChem 3000+SanChem 4000).
  • an alkaline wash at 160° F. such as SanChem 500,—a mildly alkaline phosphate cleaner
  • SanChem 1000 which is a nitric acid based deoxidizer free of fluorides, chromates and heavy metals
  • U.S. Pat. No. 4,988,396 is directed to aluminum alloys with 1% Cu. After the surface is degreased it is deoxidized using a 10% nitric acid solution (85° C., for 20 min.) followed by a deionized (DI) water rinse and immersion in 195°-212° F. DI water for 5 minutes to form a boehmite layer followed by the permanganate treatment.
  • DI deionized
  • U.S. Pat. No. 5,437,740 has several examples for anodizing aluminum and conversion coating of aluminum castings. Room temperature DI water washes after several of the treatment stages are utilized. Deoxidizing is performed using 70% HNO 3 , 2.4% HF, 27.5% water.
  • U.S. Pat. No. 5,707,465 uses a permanganate solution containing hexavalent chromium.
  • the aluminum material is degreased (using an organic solvent and a non-ionic detergent), rinsed with DI water, deoxidized using 10% HNO 3 at 70° F. for 1 minute and then rinsed with DI water. It was then treated with various different permanganate solutions.
  • U.S. Pat. No. 6,087,017 is directed to a corrosion resistant wax polyester film for aluminum.
  • the pretreatment process is relevant.
  • the aluminum panel is cleaned using a mild alkaline cleaner at 150-160° F. for 3 minute, rinsed in DI water, deoxidized in 10% HNO 3 and 3% sodium bromate at 120° F. for 5 minutes followed by a DI water rinse. This can then be followed by the application of the permanganate conversion coating at 150° F. for 1 minute.
  • U.S. Pat. No. 4,883,541 discusses the prior use of acidic deoxidizers in combination with HF. The claimed invention is then directed to acidic deoxidizers, particularly 10% HNO 3 with 3% sodium bromate or iodate.
  • U.S. Pat. No. 5,192,374 is directed to a treatment following the deoxidation step.
  • the initial cleaning steps use an alkaline cleaner (Chemidize 740) at 71° C. for 3 min. followed by a rinse for 1 min in DI water, deoxidizing at 30° C. using 10% HNO 3 +3% sodium bromate, rinsing with DI water for 1 min. and then immersion in boiling DI water for 5 minutes.
  • an alkaline cleaner (Chemidize 740) at 71° C. for 3 min. followed by a rinse for 1 min in DI water, deoxidizing at 30° C. using 10% HNO 3 +3% sodium bromate, rinsing with DI water for 1 min. and then immersion in boiling DI water for 5 minutes.
  • U.S. Pat. No. 5,417,819 is directed to compositions for desmutting aluminum surfaces comprising the use of 10-100% nitric acid and 15 gr/liter of a fluoride, the balance being water with the possible addition of H 2 SO 4 and/or H 3 PO 4 .
  • the preferred source of fluoride ion is ammonium bifluoride.
  • the surface is first treated with an alkaline cleaner solution (A31K) at 140° F. It is then immediately rinsed with water, preferably DI water. The surface is then subjected to electro-brightening followed by a DI water rinse. Desmutting is then performed for 0.5-2 min @ 60-110° F. followed by a water rinse.
  • U.S. Pat. No. 6,123,782 is directed to a process for forming a coated aluminum product comprising cleaning the surface using a nonchromated, nonsilicated alkaline cleaner followed by a hot water rinse, deoxidizing at up to 120° F. using a nonchromated deoxidizer such as SanChem 1000 (10% nitric acid, 3% sodium bromate) and then immersion in boiling deionized water for 5-10 minutes.
  • a nonchromated deoxidizer such as SanChem 1000 (10% nitric acid, 3% sodium bromate)
  • a preferred process comprises:
  • the improvement comprises the use of extensive DI water washes between each step of the process. These water washes include a combination of spray and immersion washes that appear to be critical to decontaminating the treated surface between each step to eliminate trace amounts of prior applied materials.
  • the DI water is preferably continuously reprocessed and filtered to remove undesirable ions and maintain the resistively within defined limits. Care is also taken to not use DI water at elevated temperatures so as not to react with the surface (i.e. oxidize the surface) to form boehmite.
  • a process incorporating features of the applicant's invention comprises processing through a series of wash tanks as follows:
  • all process equipment and contact surfaces are non-conductive, non-reactive material such as polypropylene, polyethylene or Teflon coated surfaces so that none of the baths or wash solutions can leach any contaminants from the processing equipment.
  • All of the DI water feed to the system as well as the DI water spray and dip tank contents used in each wash stage may begin with city and/or well water which is filtered through a initial water purification system consisting of a) 0.5 micron particulate filter, b) a D.I mixed-bed canister and c) a 0.5 micron particulate post filtration at a rate of 10. gals/min upon demand.
  • DI water Once the DI water has been processed through the initial water purification system and enters the aluminum treatment system it is preferably collected and continuously filtered serially through a) a 0.5 micron particulate filter, b) a carbon filtration canister, c) a cation bed, d) two anion beds, e) a DI mixed bed canister and f) a final 0.5 micron particulate filter at a rate of from about 3 to about 10 gal/min to maintain a water quality of at least about 50 k ohms-cm.
  • a typical DI immersion tank contains 320 gal of DI water so that the content is recycled approximately at least every 1.75 hours.
  • a typical conversion coating system could treat the rinse water simply as a waste steam.
  • the impurities from the cleanest rinse overflow to the medium purity rinse and from that into the dirtiest rinse.
  • the dirtiest rinse is treated by adjusting the pH and ORP but is discharged to the sewer on a daily basis.
  • the processed DI water entering each washing stage is maintained at a resistance of at least about 50 k ohms and at ambient temperature to minimize oxidation which can occur when clean aluminum surfaces are contacted with DI water at elevated temperatures.
  • CATIONS (Method 200.7) ANIONS (Method 300.0) As As As Element CaCo3 As Ion CaCo3 Calcium (Ca) 9 22.5 Chloride (CI 7.9 11.1 Magnesium (Mg) 4.4 18.1 Nitrate/Nitrite 1.2 4.3 Sodium (Na) 13.9 30.3 Sulfate (SO4) 4 4.2 Potassium(K) 3.7 0.1 Bi-carbonate 55.3 45.3 Barium (Ba) 0.3944 Fluoride (F) 0.2 0.50 Iron (Fe) ND Silica (SiO 2 ) 53.1 Strontium (Sr) 0.1 0.1 Manganese (Mn) ND Copper (Cu) 0.116 Zinc (Zn) 0.11 Mg/L GPG Mg/L GPG Mg/L GPG Cations 75.7 4.42 Anions 69.7 4.08 Hardness 40 2.4 Additional (CaCO3) Aluminum by ICP N.D.
  • the process incorporating features of the invention has also been found to generate less waste products, and the waste products generated are easier to handle.
  • Typical waste streams generated by the conversion coating process and DI recycling procedure are:
  • a four (4) stage system for cleaning and conversation coating aluminum alloy was utilized comprising:
  • the system includes six (6) process steps.
  • the processed aluminum alloy parts were slightly improved in appearance for a short period of time (about 3 hours), but the life of bath solutions was not adequate (about 5 hours) due to poor product surface quality. Coating voids occurred at hang points on work pieces; streakiness and rub off still existed.
  • the Sanchem 6500 solution contained approximately 3% nitric acid in addition to CC6500 surfactant. This was an improvement over the process of Example 2. However the appearance of product was still unacceptable. The stainless hangers and baskets were reacting at a different rate than the aluminum alloys thereby causing voids at contact points. Oil was still not adequately removed.
  • stage 1 The silicated alkaline cleaner (stage 1) was changed to a non-silicated alkaline cleaner. All baskets and racks were changed from stainless steel to aluminum. The steps were as follows:
  • the filtration system was then modified to increase its ability to handle the ionic loading, pump sizes were increased to improve flow through the recycle system, the efficiency and filtering capacity of the filters were increased, inert liquid contacting surfaces (tanks, hangers, baskets, etc.) were installed and instrumentation was installed to monitor and control the process, it was discovered that the overall quality of the coated products was significantly increased, by these changes, the amount of treatment materials required was reduced and the cost of operating the conversion process was reduced.
  • monitoring the flow rate and maintaining resistance of the wash solution at equal to or greater than about 50 K-ohms, it was discovered that the bath life could be increased to 256 hours, allowing processing of about 270,352 ft 2 of aluminum before product quality started to degrade.
  • wash solutions could still be used for an additional period, although with decreasing product quality, and had to be discarded and the treating system baths cleaned out at around 480 hours of processing time. Also, wash water flow rates were increased to 10 gpm without degrading the quality of the end product. It was also discovered, because the water processing reduced the corrosive nature of the wash solution, that CPVC plumbing materials were adequate for the purpose of transporting process water through the filtration system. However, PVDF or polypropylene can be used.
  • De-ionized water is naturally corrosive. While heating the rinses was expected to improve the process, because an elevated temperature would allow the parts to dry more rapidly, it was found that components retained water in cupped areas, and the remaining water would remove the finish within a couple of minutes. Accordingly, it was also unexpectedly discovered that the elimination of heated rinses significantly improved the product produced. This improvement was not offset by a slight increase in drying times which were required in the end stages of the process.
  • the invention may be further improved by adding an additional chemical bath including a sealing rinse to add further corrosion resistance and improve paint and powder coat adhesion or apply, inline, a functional coating to be used in place of paint or powder coating.
  • additional chemical bath including a sealing rinse to add further corrosion resistance and improve paint and powder coat adhesion or apply, inline, a functional coating to be used in place of paint or powder coating.
  • processing of aluminum incorporating features of the invention be limited to the chemical compounds specifically identified by trade names. Alternatives or competitive compositions may be used.
  • critical to the quality of the end product is the washing steps taken, the extensive cleaning and filtering of the DI wash solutions, and maintaining the electrical resistance of the wash solutions.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)

Abstract

A process for preparing the surface of aluminum products to receive colored coatings comprises a substantially pollution free, non-chromate pretreatment and aluminum conversion coating process. The process provides improved coating quality, increased process stability, increased throughput and extended operating life of the processing baths by controlling the electrical resistance of the deionized water used for washing the aluminum product being processed to at least about 50 k ohms and controlling the manner of washing between each step of the process.

Description

  • The invention is directed to a process for preparing the surface of aluminum to receive colored coatings. More particularly it is directed to a substantially pollution free, non-chromate pretreatment and aluminum conversion coating process which provides improved coating quality, increased process stability and extended operating life of the processing baths.
    • BACKGROUND
  • It is well known that it is particularly difficult to apply colored finishes to aluminum surfaces because of the oxide coating which naturally forms on the aluminum surfaces soon after it is formed. Accordingly, aluminum or aluminum alloy surfaces are routinely treated by applying an intermediate corrosion resistant conversion coating to the surface. A broad range of subsequent coatings can then be readily applied to the conversation coating to produce an acceptable, blemish free new surface. A common technique is to clean the aluminum surface and then apply a acid based hexavalent chromium composition to that clean surface. The chromium conversion coatings have been readily accepted because they are generally corrosion resistant and provide excellent retention of subsequent coatings. However, because of the extreme toxicity of chromium compounds and ecological problems resulting from waste disposal from aluminum treatment plants, the industry has replaced chromium conversion coating with chromium free systems.
  • A significant advance has been the use of potassium permanganate based conversion coating systems, such as developed by SanChem. Representative of such systems is the use of SanChem CC3400, a KMnO4 based compound which is chromium, cyanide and fluoride free. A typical SanChem treatment composition comprises immersion of the aluminum product in a 10% solution of SanChem CC3400+1.7 oz activator @ 135-140° F. for 1.5-2 min to produce a gold color on the aluminum; longer time provides a thicker coating with a darker yellow color. A preliminary step is cleaning the surface prior to the permanganate dips. If an alkaline cleaner is used it is usually followed by a deoxidizer or a mild, nitric acid based solution. Generally speaking the SanChem process comprises degreasing, an alkaline wash at 160° F. (such as SanChem 500,—a mildly alkaline phosphate cleaner), deoxidizing at 125° F. using SanChem 1000 which is a nitric acid based deoxidizer free of fluorides, chromates and heavy metals, forming an oxide film by immersion in DI Water @ 210° F. and a three step sealing process (SanChem 2000+SanChem 3000+SanChem 4000).
  • SanChem has several patents directed to permanganate conversion coatings of which the following are representative:
  • U.S. Pat. No. 4,711,667 describes degreasing the aluminum surface using mineral spirits followed by an alkaline wash (NaOH, alkaline NaNO3, HF, Na2CO3 or borax). This is followed by a water wash and then immersion in a bath of KMnO4 with borax, sodium benzoate or sodium carbonate, typically for 1 minute at 155° F., followed by a water rinse. All solutions were preferably silicate free.
  • U.S. Pat. No. 4,988,396 is directed to aluminum alloys with 1% Cu. After the surface is degreased it is deoxidized using a 10% nitric acid solution (85° C., for 20 min.) followed by a deionized (DI) water rinse and immersion in 195°-212° F. DI water for 5 minutes to form a boehmite layer followed by the permanganate treatment.
  • U.S. Pat. No. 5,437,740 has several examples for anodizing aluminum and conversion coating of aluminum castings. Room temperature DI water washes after several of the treatment stages are utilized. Deoxidizing is performed using 70% HNO3, 2.4% HF, 27.5% water.
  • U.S. Pat. No. 5,707,465 uses a permanganate solution containing hexavalent chromium. The aluminum material is degreased (using an organic solvent and a non-ionic detergent), rinsed with DI water, deoxidized using 10% HNO3 at 70° F. for 1 minute and then rinsed with DI water. It was then treated with various different permanganate solutions.
  • U.S. Pat. No. 6,087,017 is directed to a corrosion resistant wax polyester film for aluminum. However, the pretreatment process is relevant. The aluminum panel is cleaned using a mild alkaline cleaner at 150-160° F. for 3 minute, rinsed in DI water, deoxidized in 10% HNO3 and 3% sodium bromate at 120° F. for 5 minutes followed by a DI water rinse. This can then be followed by the application of the permanganate conversion coating at 150° F. for 1 minute.
  • U.S. Pat. No. 4,883,541 discusses the prior use of acidic deoxidizers in combination with HF. The claimed invention is then directed to acidic deoxidizers, particularly 10% HNO3 with 3% sodium bromate or iodate.
  • U.S. Pat. No. 5,192,374 is directed to a treatment following the deoxidation step. The initial cleaning steps use an alkaline cleaner (Chemidize 740) at 71° C. for 3 min. followed by a rinse for 1 min in DI water, deoxidizing at 30° C. using 10% HNO3+3% sodium bromate, rinsing with DI water for 1 min. and then immersion in boiling DI water for 5 minutes.
  • U.S. Pat. No. 5,417,819 is directed to compositions for desmutting aluminum surfaces comprising the use of 10-100% nitric acid and 15 gr/liter of a fluoride, the balance being water with the possible addition of H2SO4 and/or H3PO4. The preferred source of fluoride ion is ammonium bifluoride. The surface is first treated with an alkaline cleaner solution (A31K) at 140° F. It is then immediately rinsed with water, preferably DI water. The surface is then subjected to electro-brightening followed by a DI water rinse. Desmutting is then performed for 0.5-2 min @ 60-110° F. followed by a water rinse.
  • U.S. Pat. No. 6,123,782 is directed to a process for forming a coated aluminum product comprising cleaning the surface using a nonchromated, nonsilicated alkaline cleaner followed by a hot water rinse, deoxidizing at up to 120° F. using a nonchromated deoxidizer such as SanChem 1000 (10% nitric acid, 3% sodium bromate) and then immersion in boiling deionized water for 5-10 minutes.
  • Prior available processes still suffer from several recurring problems which are not addressed by a mere optimization of the process variables or use of alternative compositions. Initial operation of the processes set forth in each of the above references gives generally acceptable results. However, after a short period of continuous. operation the quality of the surface produced, or subsequently applied surface, becomes unacceptable due to streaks, non-uniform appearance and subsequent fading. The treatment baths have to be dumped frequently and replaced with fresh baths in order to maintain acceptable coating properties. Prior techniques and/or solutions appear to include the existence of unrecognized and unaddressed variables which contribute to a rapid decrease in product quality. Improving the process quality is not a mere matter of optimizing the operating conditions. Applicant has discovered that there is a necessity to scrupulously process, reprocess and filter the DI water to remove interfering ions which may be in the feed and rinse water feed streams, a need to limit the time and temperature of exposure of the aluminum to DI water and the importance of subsequent use of both spray and immersion treatments. Pietschmann, J. and Jehn, Hermann (Powder Coatings, Pre-Treatment and Quality Control of Aluminum for Architectural Applications, (Galvanotechnik, D-88348 Saulgau, 91, (2000) Nr. 9)) addressed the various steps of the conversion coating process, namely degreasing, pickling/etching, acid dipping if alkaline pickling is used, conversion coating and drying. The authors states that:
      • “Between the individual steps, sufficient rinsing is necessary. Rinsing is a diffusion controlled procedure. Not only the amount of water, its purity and the temperature are decisive, but also the duration of rinsing is important. The type of rinsing technique, dipping or spraying, also influences the result”
        However, the criticality of the washing steps, scrupulous reprocessing of the water and the use of DI water at ambient temperatures was not appreciated.
    DETAILED DISCUSSION
  • A preferred process, incorporating features of the invention, comprises:
      • a) a cleaning step using a commercially available alkaline composition in the manner and under conditions generally suggested by the manufacturer,
      • b) use of 10% or greater HNO3 as a deoxidizer with a 3% fluoride solution (KF preferred) at room temperature, and
      • c) application of a SanChem conversion coating (SanChem 3400) under conditions and in a manner substantially the same as recommended by the manufacturer.
  • The improvement comprises the use of extensive DI water washes between each step of the process. These water washes include a combination of spray and immersion washes that appear to be critical to decontaminating the treated surface between each step to eliminate trace amounts of prior applied materials. The DI water is preferably continuously reprocessed and filtered to remove undesirable ions and maintain the resistively within defined limits. Care is also taken to not use DI water at elevated temperatures so as not to react with the surface (i.e. oxidize the surface) to form boehmite.
  • More specifically a process incorporating features of the applicant's invention comprises processing through a series of wash tanks as follows:
      • 1) The aluminum part is immersed (agitation optional but preferred) in a first water bath containing a non-silicated, non-caustic, alkaline cleaner (such as US Specialty Color Corp Specialty 740), under conditions recommended by the supplier, namely 6-8 oz of the cleaner/gal at 140-165° F. (preferably 155° F.) for 3-7 min.
      • 2) The rinse is followed by a 20-30 sec atomized spray rinse using DI water. The aluminum part is then immersed in DI water at ambient temperature for 45-60 sec, agitation optional. The rinse is followed by a 20-30 sec atomized spray rinse using DI water.
      • 3) The aluminum part is immersed in DI water/Nitric acid (30% by Vol)/KF1 (6-8 oz/gal) at ambient temperature for 15-60 sec. The rinse is followed by a 20-30 sec atomized spray rinse using DI water which drains into that dip tank.
      • 4) The piece is then exposed to a 45-60 sec atomized spray rinse using ambient DI water, a 45-60 sec immersion in ambient DI water and a 20-30 sec atomized spray rinse using DI water.
      • 5) The aluminum piece is then immersed in DI water/SanChem CC3400 (10% by vol)+SanChem CC3400 Activator (1.7 oz/gal) at 140-165° F. (preferably 155° F.) for 2.5-4 min. Agitation optional. The appearance of the product is light yellow.
      • 6) The immersion is followed by 20-30 sec atomized spray rinse using DI water, a 30-45 sec immersion in DI water and then a 20-30 sec atomized spray rinse using DI water.
  • It is preferred that all process equipment and contact surfaces (tanks, racks, baskets, hangers, etc.) are non-conductive, non-reactive material such as polypropylene, polyethylene or Teflon coated surfaces so that none of the baths or wash solutions can leach any contaminants from the processing equipment. All of the DI water feed to the system as well as the DI water spray and dip tank contents used in each wash stage may begin with city and/or well water which is filtered through a initial water purification system consisting of a) 0.5 micron particulate filter, b) a D.I mixed-bed canister and c) a 0.5 micron particulate post filtration at a rate of 10. gals/min upon demand. Once the DI water has been processed through the initial water purification system and enters the aluminum treatment system it is preferably collected and continuously filtered serially through a) a 0.5 micron particulate filter, b) a carbon filtration canister, c) a cation bed, d) two anion beds, e) a DI mixed bed canister and f) a final 0.5 micron particulate filter at a rate of from about 3 to about 10 gal/min to maintain a water quality of at least about 50 k ohms-cm. A typical DI immersion tank contains 320 gal of DI water so that the content is recycled approximately at least every 1.75 hours. Alternatively, a typical conversion coating system could treat the rinse water simply as a waste steam. Using a three stage cascading method of rinsing, the impurities from the cleanest rinse overflow to the medium purity rinse and from that into the dirtiest rinse. The dirtiest rinse is treated by adjusting the pH and ORP but is discharged to the sewer on a daily basis. In any event, the processed DI water entering each washing stage is maintained at a resistance of at least about 50 k ohms and at ambient temperature to minimize oxidation which can occur when clean aluminum surfaces are contacted with DI water at elevated temperatures.
  • Besides controlling the quality of the DI water used throughout the system, the chemical makeup of the water feed to the system and subjected to deionization can also have an influence on the quality of the conversion coated product. A typical analysis of the feed water entering the system is given in Tables 1 and 2. Table 3 lists the analysis of that feed water returned to the system following filtering and RO treatment. Silica, an ion known to present aluminum conversion coating processing problems, while present in the feed water, has been eliminated by the filter and deionization process, and as such the water treatment process contributes significantly to the production of quality coatings.
  • It has been found that operation of a process incorporating features of the invention results in significantly increased quantities of acceptable finished product which is free of streaking, spotting, peeling and discoloration. Additionally, the life of the various solution baths (the time before the quality of the treated product is unacceptable) is increased to about 480 hours of production, resulting in a significant increase in process throughput and a commensurate reduction in the down time for cleanup and bath replacement as well as a reduction in the cost for replacement bath solutions. Still further, the frequency of discharge of bath contents, which contain EPA regulated pollutants, into the surrounding environment is significantly reduced.
    TABLE 1
    FEED WATER ANALYSIS
    Turbidity (Method 180.1) 0.1 NTU Turbidity after N.M
    filtration
    Conductivity (Method 151.0 MMHOS/CM Fst TDS by 143.7
    Color (Method 2120C) 0.0 Color after N.M
    Acidification
    pH(Method 150.1) 7.7 Tannins N.D.
    (Concentrations reported as mg/L (PPM) unless otherwise reported)
    CATIONS (Method 200.7) ANIONS (Method 300.0)
    As As As
    Element CaCo3 As Ion CaCo3
    Calcium (Ca) 9 22.5 Chloride (CI 7.9 11.1
    Magnesium (Mg) 4.4 18.1 Nitrate/Nitrite 1.2 4.3
    Sodium (Na) 13.9 30.3 Sulfate (SO4) 4 4.2
    Potassium(K) 3.7 0.1 Bi-carbonate 55.3 45.3
    Barium (Ba) 0.3944 Fluoride (F) 0.2 0.50
    Iron (Fe) ND Silica (SiO2) 53.1
    Strontium (Sr) 0.1 0.1
    Manganese (Mn) ND
    Copper (Cu) 0.116
    Zinc (Zn) 0.11
    Mg/L GPG Mg/L GPG Mg/L GPG
    Cations 75.7 4.42 Anions 69.7 4.08 Hardness 40 2.4
    Additional (CaCO3)
    Aluminum by ICP N.D. μg/L
  • TABLE 2
    FEED WATER ANALYSIS
    Inorganics
    Analyte Method Result Units PQL Dilution DLR
    Antimony (Sb) EPA200.8 ND μg/L 2 1 2
    Arsenic (As) EPA200.8 2.0 μg/L 2 1 2
    Barium (Ba) EPA200.8 34   μg/L 5 1 5
    Beryllium (Be) EPA200.8 ND μg/L 1 1 1
    Cadmium (Cd) EPA200.8 ND μg/L 1 1 1
    Chromium - EPA200.8 1.0 μg/L 1 1 1
    Total (Cr)
    Cobalt (Co) EPA200.8 ND μg/L 50 1 50
    Copper (Cu) EPA200.8 ND μg/L 5 1 5
    Lead (Pb) EPA200.8 ND μg/L 5 1 5
    Mercury (Hg) EPA200.8 ND μg/L 10 1 10
    Nickel (Ni) EPA200.8 ND μg/L 10 1 10
    Nitrate (NO3) EPA200.8 4.0 mg/L 1 1 1
    Selenium (Se)- EPA200.8 ND μg/L 2 1 2
    (Total)
    Silver (Ag) EPA200.8 ND μg/L 10 1 10
    Thallium (Tl) EPA200.8 ND μg/L 1 1 1
    Vanadium (V) EPA200.8 ND μg/L 10 1 10
    Zinc (Zn) EPA200.8 68   μg/L 50 1 50

    μg/L = micrograms/liter (ppb)

    PQL: Practical Quantitation Limi

    DLR: Detection Limit for Reporting

    PQL × Dilution

    ND: None Detected at DLR
  • TABLE 3
    POST RO TREATMENT
    Ppm Ppm
    Ion CaCO3
    Cations
    Aluminum 0.21 1.18
    Barium BDL NA
    Cadmium BDL NA
    Calcium 0.19 0.5 
    Chromium(+3) BDL NA
    Copper BDL NA
    Iron BDL NA
    Lead BDL NA
    Magnesium 0.05 0.21
    Manganese 0.08 0.15
    Nickel BDL NA
    Potassium 0.48 0.61
    Sodium 0.16 0.35
    Zinc BDL NA
    TOTAL 2.96
    CATIONS
    Strong
    Anions
    Chloride 02.1  0.30
    Chromium(+6) BDL NA
    Fluoride BDL NA
    Hydroxide BDL NA
    Nitrate 11.2  9.07
    Phosphate BDL NA
    Sulfate BDL NA
    SUB.TOTAL 9.37
    Weak
    Anions
    Bicarbonate BDL NA
    Carbonate BDL NA
    Cyanide BDL NA
    SUB-TOTAL 0.00
    TOTAL 9.37
    ANIONS
    pH 4.21 Units (by meter)
    Silica BDL mg/L SiO2
    TOC BDL mg/L
    COD NA mg/L
    Carbon NA Ml/gram
    Isotherm
    Conductivity 54.0  μmhos/cm
    Color clear
    Process Information:
    System Flowrate (gpm) 6
    Operating Temp. (° F.) 120
    Hours Operated/Day 16
    Days Operated/Week 5
    Cleaner/System Type aqueous
    Water Source DI
    Water Quality 2 MΩ-cm (Required water quality -
    50 Kohms-cm)
  • Besides providing improved quality conversion coated aluminum products, the process incorporating features of the invention has also been found to generate less waste products, and the waste products generated are easier to handle.
  • Typical waste streams generated by the conversion coating process and DI recycling procedure are:
      • 1) depleted coating/processing tank contents,
      • 2) processing tank sludge (solids or slurry deposited in the bottom of processing tanks),
      • 3) materials filtered from the DI water, and
      • 4) discharge generated by reactivating the deionizing filters.
  • By employing the DI reprocessing described herein, it has been discovered that
      • 1) The processing tank contents have an extended processing life,
      • 2) The amount of sludge generated is decreased, and can be readily and safely collected, dried and disposed of as a safe solid waste, and
      • 3) Ionic materials and organic materials discharged from the filtration system can be processed in a safe manner and the particulate filters can be dried and discarded as safe solid waste.
  • For comparison purposes, set forth below are four examples of procedures evaluated for applying a non-chromate conversion coating. These examples, while not using applicant's washing and DI water cleaning and recycling procedure, were less effective experimental attempts to obtain a suitable end product. As a result they all suffer from operating deficiencies including varying amounts of streaking, spotting, peeling and discoloration to the finished (treated) product and limitations on bath operating life. Typical prior baths and treatment procedures was found to be capable of processing only about 60,000 ft2 of acceptable product before the treatment baths had to be discarded and new solutions prepared.
    • EXAMPLE 1
  • A four (4) stage system for cleaning and conversation coating aluminum alloy was utilized comprising:
      • Stage 1—Sanchem 560 Mild acid cleaner @ 150° F. for 10 min
      • Stage 2—Hot D.I. Rinse @ 140° F. for 30-60 sec.
      • Stage 3—Sanchem CC3400 conversion coating @ 160° F. for 3 min
      • Stage 4—Hot D.I. Rinse @ 140° F. for 30-60 sec.
  • All process equipment, (hooks, baskets to tanks) was stainless steel. Appearance of the processed aluminum parts was poor, coverage was splotchy and streaky, film build was irregular and was found to rub off. The process was not adequate to remove oils and dirt on the surfaces.
    • EXAMPLE 2
  • An alkaline wash was added to the front end of the process to better remove oils and dirt. The system includes six (6) process steps.
      • Stage 1—Sanchem 8104 silicated alkaline cleaner @ 120-130° F. for 10 min.
      • Stage 2—D.I. Rinse @ 120-130° F. for 45-60 sec.
      • Stage 3—Sanchem 560 Mild acid cleaner @ 150° F. for 1-2 min.
      • Stage 4—Hot D.I. Rinse @ 140° F. for 45-60 sec.
      • Stage 5—Sanchem CC3400 conversion coating @ 160° F. for 3.0-3.5 min.
      • Stage 6—Hot D.I. Rinse @ 140° F. for 45-60 sec.
  • The processed aluminum alloy parts were slightly improved in appearance for a short period of time (about 3 hours), but the life of bath solutions was not adequate (about 5 hours) due to poor product surface quality. Coating voids occurred at hang points on work pieces; streakiness and rub off still existed.
    • EXAMPLE 3
  • The make-up of stage 3 solution was changed in an attempt to improve cleaning.
      • Stage 1—Sanchem 8104 silicated alkaline cleaner @ 120-130° F. for 10 min.
      • Stage 2—D.I. Rinse @ 120-130° F. for 45-60 sec.
      • Stage 3—Sanchem 6500 acid cleaner @ 150° F. for 1-2 min
      • Stage 4—Hot D.I. Rinse @ 140° F. for 45-60 sec.
      • Stage 5—Sanchem CC3400 conversion coating @ 160° F. for 3.0-3.5 min
      • Stage 6—Hot D.I. Rinse @ 140° F. for 45-60 sec.
  • The Sanchem 6500 solution contained approximately 3% nitric acid in addition to CC6500 surfactant. This was an improvement over the process of Example 2. However the appearance of product was still unacceptable. The stainless hangers and baskets were reacting at a different rate than the aluminum alloys thereby causing voids at contact points. Oil was still not adequately removed.
    • EXAMPLE 4
  • The silicated alkaline cleaner (stage 1) was changed to a non-silicated alkaline cleaner. All baskets and racks were changed from stainless steel to aluminum. The steps were as follows:
      • Stage 1—Specialty 740 non-silicated, non-caustic alkaline cleaner @ 150° F. for 3-7 min.
      • Stage 2—D.I. Rinse @ ambient for 45-60 sec.
      • Stage 3—De-Ox 30% Nitric Acid w/Potassium Fluoride @ ambient for 15-60 sec.
      • Stage 4—Spray rinse w/D.I. @ ambient for 45-60 sec.
      • Stage 5—D.I. Rinse @ ambient for 45-60 sec.
      • Stage 6—Sanchem CC3400 conversion coating @ 160° F. for 2.5-3.0 min.
      • Stage 7—D.I. Rinse @ ambient for 45-60 sec.
  • These changes resulted in a significant improvement in the quality of the surface of conversion coated products over the methods, of Example 1-3. The products were consistently finishing without the splotchy, streaky appearance and the coating was no longer thickening excessively, thereby eliminating flaking and rub off of the surface coating. Switching to aluminum hangers and baskets also eliminated witness marks. However, the bath life of the chemical solutions was not acceptable. After about 72 hours (or processing about 76,000 ft2 of products) streaking re-appeared and filtration cost increased significantly. The system baths had to be changed ever 120 hours (or after processing only 127,000 ft2 of aluminum parts) as product quality was no longer acceptable.
  • The filtration system was then modified to increase its ability to handle the ionic loading, pump sizes were increased to improve flow through the recycle system, the efficiency and filtering capacity of the filters were increased, inert liquid contacting surfaces (tanks, hangers, baskets, etc.) were installed and instrumentation was installed to monitor and control the process, it was discovered that the overall quality of the coated products was significantly increased, by these changes, the amount of treatment materials required was reduced and the cost of operating the conversion process was reduced. By improving the filtration as set forth herein, monitoring the flow rate and maintaining resistance of the wash solution at equal to or greater than about 50 K-ohms, it was discovered that the bath life could be increased to 256 hours, allowing processing of about 270,352 ft2 of aluminum before product quality started to degrade. The wash solutions could still be used for an additional period, although with decreasing product quality, and had to be discarded and the treating system baths cleaned out at around 480 hours of processing time. Also, wash water flow rates were increased to 10 gpm without degrading the quality of the end product. It was also discovered, because the water processing reduced the corrosive nature of the wash solution, that CPVC plumbing materials were adequate for the purpose of transporting process water through the filtration system. However, PVDF or polypropylene can be used.
  • De-ionized water is naturally corrosive. While heating the rinses was expected to improve the process, because an elevated temperature would allow the parts to dry more rapidly, it was found that components retained water in cupped areas, and the remaining water would remove the finish within a couple of minutes. Accordingly, it was also unexpectedly discovered that the elimination of heated rinses significantly improved the product produced. This improvement was not offset by a slight increase in drying times which were required in the end stages of the process.
  • It is evident from the foregoing that there are many additional embodiments of the present invention which, while not expressly described herein, are within the scope of this invention and may suggest themselves to one of ordinary skill in the art. For example, the invention may be further improved by adding an additional chemical bath including a sealing rinse to add further corrosion resistance and improve paint and powder coat adhesion or apply, inline, a functional coating to be used in place of paint or powder coating. Further, it is not intended that processing of aluminum incorporating features of the invention be limited to the chemical compounds specifically identified by trade names. Alternatives or competitive compositions may be used. However, critical to the quality of the end product is the washing steps taken, the extensive cleaning and filtering of the DI wash solutions, and maintaining the electrical resistance of the wash solutions.
  • It is therefore intended that the invention be limited solely by the appended claims.

Claims (8)

1. An improved process for the conversion coating of aluminum products comprising the steps of:
a) immersing an aluminum product in a solution for removal of dirt and oil, followed by
b) immersion in an oxidizing solution, and then followed by
c) immersion in a solution of a permanganate based conversion composition, the improvement comprising, following each of step a), b) and c) above, subjecting the aluminum product, upon removal from immersion in said solution, to at least one spray wash with deionized water and at least one immersion in deionized water, the deionized water being processed or continuously reprocessed through a series of filters and ion beds to maintain an electrical resistance of at least about 50 k ohms.
2. The process of claim 1 wherein the aluminum product, after each of steps a), b) and c) is exposed to
i. a first spray wash with deionized water,
ii. followed by immersion in deionized water, followed
iii. by a second spray wash with deionized water,
3. The process of claim 1 wherein the deionized water is maintained at an electrical resistance of at least about 50 k ohms by passing it through at least a 0.5 micron filter, a carbon filter, a cation bed, an anion bed and a DI mixed bed.
4. The process of claim 1 wherein the deionized water is processed serial through a 0.5μ filter, a carbon filter, a cation bed, two anion beds, a DI mixed bed and a 0.5μ filter.
5. The process of claim 1, wherein at least about 270,000 ft2 of exposed surface of aluminum parts is processed before streaking, spotting, peeling or discoloration of the surface appears.
6. The process of claim 1, wherein aluminum parts can be processed for at least 480 hours before unacceptable streaking, spotting, peeling or discoloration of the surface appears.
7. An improved method of applying a conversion coaching to aluminum parts, said aluminum parts being exposed to treatment baths for a cleaning the parts, b) oxidizing the exposed surface of the parts and c) conversion coating the parts,
wherein the parts are spray washed and immersed in deionized water between each treatment bath exposure, the deionized water having an electrical resistance equal to or greater than about 50 k ohms.
8. The improved method of claim 7 wherein the deionized water is maintained at a resistance of at least about 50 k ohms by continuously recirculating the water through at least a 0.5μ filter, a carbon filter, a cation bed, an anion bed and a mixed bed at a flow rate from about 3 gal/min to about 10 gal/min.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007091945A1 (en) * 2006-02-06 2007-08-16 Altitech Ab Method, composition and use for obtaining an anti-corrosion surface layer on metals
US20080145542A1 (en) * 2006-12-15 2008-06-19 Ford Global Technologies, Llc Method for preparing a brazed surface for receiving a coating
US20110159636A1 (en) * 2008-09-01 2011-06-30 Merck Patent Gesellschaft Mit Beschrankter Haftung Edge deletion of thin-layer solar modules by etching
CN102124144A (en) * 2008-08-12 2011-07-13 汉高股份有限及两合公司 Successive corrosion-protecting pre-treatment of metal surfaces in a multi-step process
CZ305721B6 (en) * 2014-11-11 2016-02-17 Univerzita J. E. Purkyně V Ústí Nad Labem Metal plating method of metal molds made of Al-Mg and Al-Si alloy-types, especially for producing motor vehicle tires in automobile industry
US20160356427A1 (en) * 2006-11-27 2016-12-08 Frank Levy Disposable cartridge for holding compressed medical gas
US20180087718A1 (en) * 2006-11-27 2018-03-29 Frank Levy Disposable single-use cartridge for holding compressed medical gas

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2016257686B2 (en) 2015-05-01 2019-09-26 Novelis Inc. Continuous coil pretreatment process

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3728188A (en) * 1971-07-29 1973-04-17 Amchem Prod Chrome-free deoxidizing and desmutting composition and method
US4435223A (en) * 1981-06-24 1984-03-06 Amchem Products, Inc. Non-fluoride acid compositions for cleaning aluminum surfaces
US4711667A (en) * 1986-08-29 1987-12-08 Sanchem, Inc. Corrosion resistant aluminum coating
US4883541A (en) * 1989-01-17 1989-11-28 Martin Marietta Corporation Nonchromate deoxidizer for aluminum alloys
US5124192A (en) * 1989-11-15 1992-06-23 General Electric Company Plastic mold structure and method of making
US5128043A (en) * 1991-02-13 1992-07-07 Wildermuth Glen W Method and apparatus for purifying liquids
US5192374A (en) * 1991-09-27 1993-03-09 Hughes Aircraft Company Chromium-free method and composition to protect aluminum
US5417819A (en) * 1994-01-21 1995-05-23 Aluminum Company Of America Method for desmutting aluminum alloys having a highly reflective surface
US5437740A (en) * 1993-04-21 1995-08-01 Sanchem, Inc. Corrosion resistant aluminum and aluminum coating
US5707465A (en) * 1996-10-24 1998-01-13 Sanchem, Inc. Low temperature corrosion resistant aluminum and aluminum coating composition
US5725683A (en) * 1996-03-28 1998-03-10 Aluminum Company Of America Manufacturing clear coated aluminum alloy lighting sheet
US5988396A (en) * 1997-06-19 1999-11-23 Isg Resources, Inc. Ultrasonic conditioning and wet scrubbing of fly ash
US6087017A (en) * 1998-06-15 2000-07-11 Sachem, Inc. Corrosion resistant coating for aluminum and aluminum alloys
US6123782A (en) * 1994-05-27 2000-09-26 Raytheon Company Nonchromated, primer-free, surface preparation for painting, powder coating and adhesive bonding
US20020096230A1 (en) * 2000-03-20 2002-07-25 Hardin Simon Gerard Process and solution for providing a conversion coating on a metallic surface II
US6503565B1 (en) * 1993-09-13 2003-01-07 Commonwealth Scientific And Industrial Research Organisation Metal treatment with acidic, rare earth ion containing cleaning solution

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4988396A (en) * 1989-04-26 1991-01-29 Sanchem, Inc. Corrosion resistant aluminum coating composition
JP2947695B2 (en) * 1993-07-30 1999-09-13 日本ペイント株式会社 Aqueous cleaning aqueous solution of aluminum-based metal and cleaning method thereof

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3728188A (en) * 1971-07-29 1973-04-17 Amchem Prod Chrome-free deoxidizing and desmutting composition and method
US4435223A (en) * 1981-06-24 1984-03-06 Amchem Products, Inc. Non-fluoride acid compositions for cleaning aluminum surfaces
US4711667A (en) * 1986-08-29 1987-12-08 Sanchem, Inc. Corrosion resistant aluminum coating
US4883541A (en) * 1989-01-17 1989-11-28 Martin Marietta Corporation Nonchromate deoxidizer for aluminum alloys
US5124192A (en) * 1989-11-15 1992-06-23 General Electric Company Plastic mold structure and method of making
US5128043A (en) * 1991-02-13 1992-07-07 Wildermuth Glen W Method and apparatus for purifying liquids
US5192374A (en) * 1991-09-27 1993-03-09 Hughes Aircraft Company Chromium-free method and composition to protect aluminum
US5437740A (en) * 1993-04-21 1995-08-01 Sanchem, Inc. Corrosion resistant aluminum and aluminum coating
US6503565B1 (en) * 1993-09-13 2003-01-07 Commonwealth Scientific And Industrial Research Organisation Metal treatment with acidic, rare earth ion containing cleaning solution
US5417819A (en) * 1994-01-21 1995-05-23 Aluminum Company Of America Method for desmutting aluminum alloys having a highly reflective surface
US6123782A (en) * 1994-05-27 2000-09-26 Raytheon Company Nonchromated, primer-free, surface preparation for painting, powder coating and adhesive bonding
US5725683A (en) * 1996-03-28 1998-03-10 Aluminum Company Of America Manufacturing clear coated aluminum alloy lighting sheet
US5707465A (en) * 1996-10-24 1998-01-13 Sanchem, Inc. Low temperature corrosion resistant aluminum and aluminum coating composition
US5988396A (en) * 1997-06-19 1999-11-23 Isg Resources, Inc. Ultrasonic conditioning and wet scrubbing of fly ash
US6087017A (en) * 1998-06-15 2000-07-11 Sachem, Inc. Corrosion resistant coating for aluminum and aluminum alloys
US20020096230A1 (en) * 2000-03-20 2002-07-25 Hardin Simon Gerard Process and solution for providing a conversion coating on a metallic surface II

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007091945A1 (en) * 2006-02-06 2007-08-16 Altitech Ab Method, composition and use for obtaining an anti-corrosion surface layer on metals
US20160356427A1 (en) * 2006-11-27 2016-12-08 Frank Levy Disposable cartridge for holding compressed medical gas
US20170159887A1 (en) * 2006-11-27 2017-06-08 Frank Levy Disposable cartridge for holding compressed medical gas
US20180087718A1 (en) * 2006-11-27 2018-03-29 Frank Levy Disposable single-use cartridge for holding compressed medical gas
US20080145542A1 (en) * 2006-12-15 2008-06-19 Ford Global Technologies, Llc Method for preparing a brazed surface for receiving a coating
US8440264B2 (en) * 2006-12-15 2013-05-14 Ford Global Technologies, Llc Method for preparing a brazed surface for receiving a coating
CN102124144A (en) * 2008-08-12 2011-07-13 汉高股份有限及两合公司 Successive corrosion-protecting pre-treatment of metal surfaces in a multi-step process
US20110189401A1 (en) * 2008-08-12 2011-08-04 Henkel Ag & Co. Kgaa Successive corrosion-protecting pre-treatment of metal surfaces in a multiple-step process
US8679586B2 (en) * 2008-08-12 2014-03-25 Henkel Ag & Co. Kgaa Successive corrosion-protecting pre-treatment of metal surfaces in a multiple-step process
US20110159636A1 (en) * 2008-09-01 2011-06-30 Merck Patent Gesellschaft Mit Beschrankter Haftung Edge deletion of thin-layer solar modules by etching
US8497215B2 (en) * 2008-09-01 2013-07-30 Merck Patent Gmbh Edge deletion of thin-layer solar modules by etching
CZ305721B6 (en) * 2014-11-11 2016-02-17 Univerzita J. E. Purkyně V Ústí Nad Labem Metal plating method of metal molds made of Al-Mg and Al-Si alloy-types, especially for producing motor vehicle tires in automobile industry

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