A Dual Vessel System of Phosphating Ferrous Alloys under Steam Pressure
Abstract
A dual vessel system of phosphating ferrous alloys under steam pressure was investigated for the application of high temperature corrosion resistant coatings on a continuous production-type basis. In this system, the phosphating bath can be transferred from one vessel to another using differential steam pressure. Either vessel can be used as a phosphating or holding tank and the bath can be maintained continuously under pressure. Sludge can be removed from the bath during the transfer of solution to the other vessel, and the bath can be used continuously on a production-type basis. Four types of manganese enriched baths were used in testing the dual vessel system. Salt spray corrosion testing was divided into two groups: unheated panels and panels heated to 450 F for one hour. Results from the manganese tartrate enriched bath best illustrated the success of pressure phosphating using consecutive production-type runs in the dual vessel system. For this manganese tartrate bath, 90% of the heated and 81% of the unheated sets of panels passed a minimum 100-hour salt spray resistance test. Continuous control of free (to less than 3.5 points) and total acid (to above 30 points) values and proper maintenance of the bath with chemical additions after each processing period are needed for reproducible superior heat and corrosion resistant phosphate coatings.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1979
- Accession Number
- ADA079547
Entities
People
- Henry Crain
- Linden H. Wagner