An Aluminum Ion Vapor Deposition (AIVD) System to Reduce Waste Generation

Among its many activities, the U.S. Army Environmental Center (USAEC) demonstrates and promotes the use of innovative technologies that reduce waste and prevent pollution at Army depots. USAEC recently supported the implementation of an Aluminum Ion Vapor Deposition (AIVD) system, which could help reduce waste generated during industrial plating operations.

Waste Generation

Metal plating operations are a typical activity at Army depots. Metal parts traditionally have been electroplated with cadmium, which protects surfaces from corrosion. However, cadmium is a toxic metal, and electroplating generates significant amounts of waste, such as spent plating baths, sludge, and rinse water. The U.S. Environmental Protection Agency (EPA) regulates this cadmium-contaminated waste as hazardous waste under the Resource Conservation and Recovery Act (RCRA).The government also regulates sludge created by treating spent solutions and rinse waters in on-site industrial wastewater treatment plants, as well as cadmium-containing fumes, dust and mist that result from industrial operations. Further, the Occupational Safety and Health Administration regulates cadmium exposure in the workplace.

AIVD offers several advantages over cadmium electroplating:

The process requires no hazardous materials and generates no hazardous waste. AIVD prevents employee exposure to hazardous materials, ends the duty of loading waste for transport to a wastewater treatment plant, and eliminates the need for environmental permits.
In acidic environments, AIVD prevents corrosion better than cadmium coatings.
AIVD coatings stand up to higher temperatures (925 degrees Fahrenheit, compared to 450 degrees Fahrenheit for cadmium).
AIVD allows for thicker coatings, and provides a more uniform coating on edges and corners than solution electroplating.

The difficulties of handling toxic materials and the increasing costs of managing hazardous waste provide incentives for minimizing hazardous waste generation and preventing pollution at the source. Aluminum surface coatings can replace cadmium in many applications. AIVD is a clean technology that shops can use to apply coatings of aluminum to metal, plastics, composites and other substrates.

The System

The major components of an AIVD system include:

An IVD vacuum (coating) chamber.
A positive pressure clean room with air conditioning and controls for dust and humidity.
A two-stage vacuum pump system to evacuate the coating chamber to 10-6 torr.
A cryogenic cooler to remove excess water vapor and reduce pump-down time.
A parts rack with air-flotation transport dollies.
A barrel coater for small parts.
Specialty racks for long or large parts.
Glove boxes for grit blasting and peening.
A high-voltage power supply.
A computer controller.
Proven Results

USAEC recently provided technical support for the implemention of an AIVD system at Tobyhanna Army Depot, Pa. The center documented this assistance in the report, Technical Support for Implementation of Aluminum Ion Vapor Deposition at Tobyhanna Army Depot (Report No. SFIM-AEC-ET-CR-96006, NTIS Order# ADA 308911). This report includes a bid specification for the AIVD system, an economic analysis of the AIVD system, a work order for system installation, and information on AIVD technology and coatings.

For more information contact:
U.S. Army Environmental Hotline
(800) USA-3845, DSN 584-1699

Pollution Prevention
Technology