Chapter 6, Problem 3CS

Surface Treatment—Depending on the material selected in part 1, it might be necessary to apply some form of coating or surface treatment to suppress corrosion and possible rust marks on the paper.

1. In addition to corrosion resistance, are there any other surface requirements?
2. What types of surface treatments would you consider to be possibilities?
3. Which of the preceding possibilities would you recommend?
4. At what stage of manufacture do you want to perform the surface treatment and by what method? Give consideration to the following observations:
   • If applied to the starting wire, the coating will have to have sufficient ductility to endure the shaping operation.
   • If applied to the starting wire, the sheared ends will not be coated.
   • If applied to the finished product, the gap between the parallel wires might be bridged or might not be coated.
   • If the coating is applied at elevated temperature, the coating process might anneal the underlying wire.
   • Some coating operations might affect the ductility of the underlying material, such as hydrogen embrittlement.
   • Some processes, such as hot dip immersion in molten metal, apply a thicker than desired coating. If this is applied earlier in the wireâ€�making process, will the subsequent wire drawing operations maintain the integrity of the coating, or simply wipe off the deposited surface?

5. Would stainless steel be a desirable material for paper clip manufacture? Which of the types or varieties would you recommend (ferritic, austenitic, or martensitic)? Would there be any advantage to having a nonmagnetic austenitic paper clip?