Date of Award

Spring 1952

Document Type

Thesis

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical Engineering

Abstract

Molydbenum, due to its high temperature properties, and potential supply, is becoming a very important structural material, particularly in the field of electronics, however, it is not new in this part of industry. As temperatures go higher in various fields, the need for satisfactory materials becomes of paramount importance.

One of the ways in which to overcome the disadvantages of poor stability, brazing difficulties, and surface resistance to high frequency conduction, is by electroplating. Until recently there has been no satisfactory method for obtaining adherent deposits. The purpose of this report has been to investigate these recent processes and devise a method by which the average plating installation may obtain adherent electroplated deposits on molybdenum.

The following method, devised by the author, was found to give satisfactory adherence of nickel flexible sheet molybdenum: After degreasing, the part is etched anodically in 95% sulfuric acid for one minute at 9 volts and then rinsed in cold running water. It is then rinsed in an ammonium hydroxide solution, followed by cold running water. The molybdenum is then treated cathodically for one minute at 9 to 10 volts in 95% sulfuric acid. After this, it is rinsed in cold water and nickel plated in a low ph Watt's bath.

The following method, also devised by the author, was found to be satisfactory for nickel plating rigid pieces of molybdenum for brazing purposes. After degreasing, the part is etched in a solution of three parts water, two parts sulfuric acid, and one part nitric acid. It is then rinsed and dipped in hot hydrochloric acid. The part is rinsed again and plated with nickel in a low ph Watt's bath.

The following method devised by A. Korbelak (22) of Westinghouse Corporation is satisfactory for obtaining adherent nickel plating on flexible sheet molybdenum. After degreasing, the part is etched anodically in 60% sulfuric acid for 30 seconds at 10 volts. After rinsing and dipping in caustic bath (caustic soda, commercial cleaner or equivalent), the part is neutralized in a 5-10% sulfuric acid dip. After rinsing, the part is chromium plated for 20-60 seconds at 1 amp/in2. The molybdenum is then rinsed and transferred to a high chloride nickel strike (Wood's bath).

Another method for obtaining adherent deposits on molybdenum is a method used by RCA Victor. This involves spraying the part with a mixture of nickel and silver oxides and firing in line H2 at 250°C. for 15 minutes. The part may then be plated with any desired metal.

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