Plating on tungsten carbide
1
Shop Problems Plating and Anodizing Use the Shop Problem Card in this issue for free expert advice. Tarnishing of Silver-Plated Earrings Q . We plate white metal castings . using a bright cyanide silver ba . The problem is that the plated pieces become yellow after a short time. We check the anodic/cathodic area, pK solution concentration, brightener, etc. and everything seems fine. The bath has operated for five months and we have plated about 60,000 earrings. Please tell me how to avoid this problem or if it is possible to protect the silver with a cheap immer- sion coating. J.C. A . There are a number of propri- . etary tarnish inhibitors avail- able that will help to prevent the yel- lowing of silver deposits, which is caused by sulfur-bearing materials. These inhibitors are of three basic types-chromates, mercaptans, or im- mersion tin deposits. In this case, the organic mercaptans would probably be best in view of the skin contact. Infor- mation on these materials can be ob- tained from one of the companies listed under Silver Plating Processes in the Metal Finishing Guidebook and Directory. (Page 859 in the 1997 edi- tion.) If the earrings are wrapped in paper or clipped onto cardboard, you should be using a treated paper/cardboard for this purpose. Normal paper/cardboard is manufactured from sulfite pulp, which gives off sulfur enhancing the tarnishing action. Stripping Anodized Aluminum Coatings Q . I’m looking for information on . removing anodized coatings from aluminum wheels. Any details you can provide would be helpful. P.I. A . Although it’s possible to rap- . idly remove anodic coatings from aluminum in a caustic solution, there would also be attack of the sub- strate. Try the solution used for mea- surement of the coating mass of anodic coatings on aluminum as provided in ASTM B 137. This consists of 20 grams of chromic acid anhydride (CrO,) and 35 ml of 85% by weight orthophosphoric acid per liter of solu- tion. Immerse the part in this solution for 5 minutes at 100°C. GRIND OUT MORE PROFIT DOLLARS You need quick service and fast delivery of coated-abrasive FLAPWHEELS-we need more customers like you-we need each Schaffner is a relatively small and hungry compa will deliver high-quality FLAPWHEELS to you faster than your present supplier. Call us today to start realizing the savings possible from lowering your inventory investment. For all your buffing and polishing needs. MANUFACTURING PLANTS Emsworth, Pittsburgh, PA (Zip) 15202 North Delta Dr., Jackson, MS (Zip) 39213 I HEADQUARTERS OFFICE Pittsburgh, PA 15202 412-761-9902 FAX: 412-761-8998 Circle 101 on readerinformation card This solution dissolves the anodic coating with no significant attack of the substrate aluminum. Be sure to uti- lize proper personal protection and conduct the stripping under a hood in a well ventilated area. Plating on Tungsten Carbide Q . I am attempting to electroless . nickel plate a 6% cobalt tung- sten carbide material. Using an acid cleaner and metal cleaner blisters sometimes appear, is there a better pro- cedure for electroless nickel plating this material? R.S. A . A cycle incorporating a Wood’s . nickel strike is suggested. Alka- line clean, alkaline electroclean, 50% by volume hydrochloric acid dip, Wood’s nickel strike, electroless nickel plate. The Wood’s nickel strike is op- erated at room temperature at a current density of 20 to 200 A/f? for 1 to 4 minutes. A typical strike formulation would include 32 oz/gal of nickel chlo- ride and 16 ozlgal hydrochloric acid. MC Handbook of Efiluent Treatment and Recycling for the Metal Finishing Industry by L Hmtingn 790 pages $120.00 This book includes all aspects of the treatment of efluents arising from various branches of the metal- working and metal-finishing industries. In sympa- thy with modem legislative trends, the emphasis is on means of avoiding or at least minimizing the production of effluent. This includes increasing the life process and other baths as well as recycling, whenever possible. Send Orders to: METAL FINISHING 660 White Plains Rd., Tarrytown, NY 10591-5153 For faster scrvicc,call (914) 333-2578 or FAX your order to (914) 333-2570 All ordas must be prepaid Please include $5.00shipping and handlii for delivery of each book via UPS in the U.S., 110.00 for each book shipped cxpmss to Cam& and SZO.00 for each bmk shipped express to all other countries. 134 METAL FINISHING l JUNE 1997
Transcript of Plating on tungsten carbide
Shop Problems Plating and Anodizing Use the Shop Problem Card in this issue for free expert advice.
Tarnishing of Silver-Plated Earrings
Q
. We plate white metal castings . using a bright cyanide silver
ba . The problem is that the plated pieces become yellow after a short time. We check the anodic/cathodic area, pK solution concentration, brightener, etc. and everything seems fine. The bath has operated for five months and we have plated about 60,000 earrings. Please tell me how to avoid this problem or if it is possible to protect the silver with a cheap immer- sion coating.
J.C.
A . There are a number of propri- . etary tarnish inhibitors avail-
able that will help to prevent the yel- lowing of silver deposits, which is caused by sulfur-bearing materials. These inhibitors are of three basic types-chromates, mercaptans, or im- mersion tin deposits. In this case, the organic mercaptans would probably be best in view of the skin contact. Infor- mation on these materials can be ob- tained from one of the companies listed under Silver Plating Processes in the Metal Finishing Guidebook and
Directory. (Page 859 in the 1997 edi- tion.)
If the earrings are wrapped in paper or clipped onto cardboard, you should be using a treated paper/cardboard for this purpose. Normal paper/cardboard is manufactured from sulfite pulp, which gives off sulfur enhancing the tarnishing action.
Stripping Anodized Aluminum Coatings
Q . I’m looking for information on . removing anodized coatings
from aluminum wheels. Any details you can provide would be helpful.
P.I.
A . Although it’s possible to rap- . idly remove anodic coatings
from aluminum in a caustic solution, there would also be attack of the sub- strate. Try the solution used for mea- surement of the coating mass of anodic coatings on aluminum as provided in ASTM B 137. This consists of 20 grams of chromic acid anhydride (CrO,) and 35 ml of 85% by weight orthophosphoric acid per liter of solu- tion. Immerse the part in this solution for 5 minutes at 100°C.
GRIND OUT MORE PROFIT DOLLARS
You need quick service and fast delivery of coated-abrasive FLAPWHEELS-we need more customers like you-we need each
Schaffner is a relatively small and hungry compa will deliver high-quality FLAPWHEELS to you faster than your present supplier. Call us today to start
realizing the savings possible from lowering your inventory investment.
For all your buffing and polishing needs.
MANUFACTURING PLANTS
Emsworth, Pittsburgh, PA (Zip) 15202
North Delta Dr., Jackson, MS (Zip) 39213
I HEADQUARTERS OFFICE Pittsburgh, PA 15202
412-761-9902 FAX: 412-761-8998
Circle 101 on reader information card
This solution dissolves the anodic coating with no significant attack of the substrate aluminum. Be sure to uti- lize proper personal protection and conduct the stripping under a hood in a well ventilated area.
Plating on Tungsten Carbide
Q . I am attempting to electroless . nickel plate a 6% cobalt tung-
sten carbide material. Using an acid cleaner and metal cleaner blisters sometimes appear, is there a better pro- cedure for electroless nickel plating this material?
R.S.
A . A cycle incorporating a Wood’s . nickel strike is suggested. Alka-
line clean, alkaline electroclean, 50% by volume hydrochloric acid dip, Wood’s nickel strike, electroless nickel plate. The Wood’s nickel strike is op- erated at room temperature at a current density of 20 to 200 A/f? for 1 to 4 minutes. A typical strike formulation would include 32 oz/gal of nickel chlo- ride and 16 ozlgal hydrochloric acid.
MC
Handbook of Efiluent Treatment and Recycling for the Metal
Finishing Industry by L Hmtingn 790 pages $120.00
This book includes all aspects of the treatment of efluents arising from various branches of the metal- working and metal-finishing industries. In sympa- thy with modem legislative trends, the emphasis is on means of avoiding or at least minimizing the production of effluent. This includes increasing the life process and other baths as well as recycling, whenever possible.
Send Orders to: METAL FINISHING 660 White Plains Rd.,
Tarrytown, NY 10591-5153 For faster scrvicc, call (914) 333-2578 or FAX your order to (914) 333-2570
All ordas must be prepaid Please include $5.00 shipping and handlii for delivery of each book via UPS in the U.S., 110.00 for each book shipped cxpmss to Cam& and SZO.00 for each bmk shipped express to all other countries.
134 METAL FINISHING l JUNE 1997
