Combines Methods with VCI for Long Duration Corrosion Protection of Military Equipment

A significant portion of military equipment needs to be stored for twenty or more years. The storage environment is often hostile. Existing corrosion protection methods using volatile corrosion inhibitors (VCI) generally have effective service life of approximately five years. The effectiveness of existing VCI in a variety of industrial applications encountered in 27 countries over the last 20 years is discussed. New methods, which allow the range of VCI applications to be reliably extended, are described. These new technologies increase the efficiency and service life and decrease the total cost of corrosion protection of military, automotive and railway equipment, electronic systems and devices, etc.

INTRODUCTION

More than 1000 types of VCI compounds are known, but only a fraction of them are efficient, cost effective and environmentally friendly. VCI's are a class of corrosion inhibiting compounds with a finite vapor pressure. The chemical protection is delivered through space by the VCI vapor condensing on a metal's surface and creating a protective film.

VCI's are useful as part of efficient protection systems for ferrous and nonferrous metals. Many of the applications utilize VCI impregnated PE packaging but a variety of other delivery methods have been used [1-6].

VCI's have significant properties (Figure 1,2). The corrosion protection radius depends on the vapor pressure of the VCI's. The service life of existing VCI systems is in the range of 1 to 5 years. The corrosion protection (CP) mechanism depends on the VCI compounds used and the characteristics of the metal being protected. Figure 2 shows the different types of inhibitors. This understanding allows us to choose the best inhibiting system. There is a need for a system that protects items for a longer period of time than the current VCI methods. The new methods should retain many of the advantages of the traditional VCI methods. These advantages include self- application of protection, as well as, immediate use of the protected item upon removal from the protection system. 1