US20050238532A1

US20050238532A1 - Process for protecting an outer surface of a non passive metal object

Info

Publication number: US20050238532A1
Application number: US11/106,483
Authority: US
Inventors: Gerrit Walker
Original assignee: DaimlerChrysler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2004-04-17
Filing date: 2005-04-15
Publication date: 2005-10-27
Also published as: DE102004018624B4; DE102004018624A1

Abstract

The invention relates to a method for the protection of objects bearing metals, especially non-passivatable metals. Corrosion inhibitors (VCI materials) are put into a carrier loaded with the objects to be protected, the amount of VCI material being chosen such that the interior vapor phase of the carrier has always sufficient VCI material during the entire period of transportation and storage. An inhibitor gas and/or inhibitor fluid is, or may serve as a carrier for, the VCI material. The treatment with the inhibitor gas and/or inhibitor fluid containing the VCI material may be performed before the carrier is sealed and may be performed on the exposed surface of the object and/or the inside surface of the carrier.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of German Patent Document No. 10 2004 018 624.3-45, filed Apr. 17, 2004, the disclosure of which is expressly incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a method for the protection of objects bearing metals, especially metals which cannot be passivated, in which the objects are placed in a carrier. Corrosion inhibitors in a vapor phase, are placed in the carrier and the carrier, loaded with the objects and the VCI materials, is closed. The amount of VCI material is chosen such that the interior vapor phase in the carrier always has sufficient VCI material throughout the entire transportation and storage period.

BACKGROUND OF THE INVENTION

Several methods for the protection of metal objects by means of so-called vapor phase corrosion inhibitors (volatile corrosion inhibitors, hereinafter called “vacuum corrosion inhibitors”—VCI materials hereinafter—for simplicity) are disclosed in DE 198 34 226 C. An ISO definition of such materials can be found in that patent. Furthermore, literature is cited therein, in which various VCI materials are mentioned. It is common to all these methods that the materials are placed in a carrier, and the carrier, charged with VCI, is closed. When the interior vapor phase in the carrier is especially saturated with VCI materials, these precipitate onto the surface of the object. If the input VCI material is proportioned such that sufficient VCI material is present during the entire transport and storage period, the protection of the object during this time is at least improved. At least in the case of large numbers and/or voluminous objects, the loading, removal and disposal of the VCI materials has long caused a great expenditure of time and labor, so that these protective measures entail a considerable financial expenditure.
For the protection of printed circuits (IC's), it is disclosed in JP 56122884 A to dissolve a certain VCI material in a hydrohalide, apply this inhibiting liquid directly onto the metal, and then seal the circuit in a known manner. In the case of a procedure according to JP 56122884 A, however, the advantage of the principle of the volatile corrosion inhibitors of VCI materials is no longer utilized. Instead, the protection serves only for the directly coated circuit. In the case of large quantities and objects of great bulk, such protection of objects which are moved into or stored in carriers, especially those that are repeatedly used is extremely inefficient.

SUMMARY OF THE INVENTION

One purpose of certain embodiments of the invention is to provide a method whereby objects in large numbers and/or of bulky dimensions can be protected in a lower-cost way.
The problem is solved by the invention with a method having the features disclosed herein. In particular, in one embodiment, a method for protecting objects bearing metals is provided and comprises the steps of: placing the objects in a carrier; providing an inhibitor gas or inhibitor fluid containing vapor-phase corrosion inhibitors and closing the carrier loaded with the objects and the inhibitor gas or inhibitor fluid, wherein the amount of vapor-phase corrosion inhibitors is adequate to ensure sufficient vapor-phase corrosion inhibitors are present to inhibit corrosion of the objects to be protected. By this direct treatment at least of areas of the object's surface that are exposed in the carrier and/or of the interior surface of the carrier, the application of the VCI material can be performed in a simple, automatable and low-cost manner.
The term, “treatment” is to be understood particularly to mean the application of a liquid, a gas, an aerosol or the like. The application can be performed especially by wetting, by spraying, by brushing, by instillation etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings, in which:
FIG. 1 shows the bottom tray of a carrier;
FIG. 2 shows a middle tray of a carrier;
FIG. 3 shows an apparatus for putting VCI material into a carrier; and
FIG. 4 shows another embodiment of the apparatus of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIGS. 1-4, a crankshaft 5 is provided as the object to be protected in one embodiment. Instead of the crankshaft 5, any desired object can be used as the object to be protected, which has at least in some areas a freely accessible metal surface. For instance, the object can be a camshaft and/or an engine and/or a cylinder head. As metals, all metals are to be understood which preferably can not be passivated against corrosion phenomena, such as aluminum, for example.
In FIG. 1 there is represented a bottom tray 1 of a carrier for crankshafts 5. The inside contours of the bottom tray 1, which forms the bottom inside surface 3 of the carrier, is configured to accommodate several crankshafts in defined positions, and has a circumferential marginal area. The bottom of the bottom tray 1 is preferably planar so that it can be placed on a pallet 6. For a better hold on a pallet 6 the bottom side of the bottom tray 1 can advantageously have a shape which is shaped negatively to that of the pallet 6.
In FIG. 2 a middle tray 2 is represented. The middle tray 2 has on its bottom side, which forms the upper inside surface 4 of a conveyor belt, a shape which is adapted to the crankshafts 5 which are to be held and which project above the bottom tray 1.
The upper side of the middle tray 2 is made to match the inside upper surface 3 of the bottom tray 1 and forms therewith the inside bottom surface of the transportation container next following.
Externally, the bottom side of the middle tray 2 also has a circumferential margin which, when the carrier is closed, rests on the corresponding margin of the bottom tray 1, preferably at least largely sealingly. Thus the bottom side of the middle tray 2 forms together with the bottom tray an especially closed cavity of the carrier. The gas volume of the carrier has, in any case, little gas exchange with the outer gas space. Thus it is possible to saturate the gas phase of this cavity with a particular substance, with VCI material in the case of the present invention, e.g., by sublimation or vaporization.
A top tray (not shown) is logically shaped on its bottom to mate with the bottom of a middle tray 2. In this way it is possible, as shown in FIG. 4, to combine a plurality of carriers into a stack. The bottom carrier of the transport stack is formed of the bottom tray 1 and a middle tray 2, while the final, upper carrier of the transport stack is formed by the upper tray (not shown) and a middle tray 2. The carriers arranged between them are formed by two middle trays 2, the lower tray 2 in each case being the bottom tray and the middle tray 2 above it being the upper tray of this carrier.
The bottom tray 1 is placed on a corresponding pallet 6 and the crankshafts 5 are laid on the upper inside surface 3 of the bottom tray 1. By the shape of the upper inside surface 3 of the bottom tray 1 the crankshafts 5 are at least held approximately in place. Loading the crankshafts is preferably automated, especially by means of an industrial robot 8.
After the crankshafts 5 are laid in place, preferably fluid VCI material and/or VCI material 7 dispersed in a liquid is sprayed over the bottom tray 1, so that the crankshafts 1 are contacted by it at least in areas.
In order that the very least contamination of the environment will take place, the VCI material 7 is applied effectively by means of a low-pressure system.
Instead, or in addition, a controlled injection of VCI material 7 can be made at specific places on the crankshafts 5 and/or on the inside surface 3.
The input or application of VCI material 7 can also be performed effectively with an industrial robot 8, preferably with the same one that is provided for the assembly.
After the application of the VCI material 7 has been completed, the middle tray 2 is placed sealingly onto the bottom tray 1 and the loading of a second layer can be performed.
In the closed carrier, the gas space is saturated with the VCI material 7, which deposits itself onto the metal surfaces of the crankshafts 5.
The procedure is continued until the stacking of several carriers one over the other has ended and terminates with the laying-on of the top tray.
The amount and/or the concentration of VCI material 7 is especially chosen so that the interior vapor phase of the carrier will always have sufficient VCI material throughout the transportation and storage period.
Furthermore, the rate of injection is preferably such that, after transportation and additional storage time, the VCI material 7 has at least been largely used up. Thus the crankshafts can be removed for further processing, and the different trays 1 and 2 can be reused without further operations.
In contrast, or in addition, the inside surfaces 3 and 4 of the carrier can be treated with the inhibitor gas and/or inhibitor fluid before the carrier is loaded or reloaded.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Claims

1. A method for protecting objects bearing metals comprising the steps of:

placing the objects in a carrier;

providing an inhibitor gas or inhibitor fluid containing vapor-phase corrosion inhibitors and

closing the carrier loaded with the objects and the inhibitor gas or inhibitor fluid, wherein the amount of vapor-phase corrosion inhibitors is adequate to ensure sufficient vapor-phase corrosion inhibitors are present to inhibit corrosion of the objects to be protected.

2. The method of claim 1 wherein said metals are non-passivatable metals.

3. The method of claim 1, wherein the inhibitor gas or inhibitor fluid is provided on at least a metal surface of the object to be protected.

4. The method of claim 1, wherein the inhibitor gas or inhibitor fluid is provided on the inside surface of the carrier.

5. The method of claim 1, wherein the inhibitor gas or inhibitor fluid is provided on only the inside surface of the carrier.

6. The method of claim 1, wherein the inhibitor gas or inhibitor fluid is provided only after the carrier is completely loaded.

7. The method of claim 1, wherein the step of provided the inhibitor gas or inhibitor fluid comprises spraying the inhibitor gas or inhibitor fluid onto the object or into the carrier.

8. The method of claim 1, further comprising the step of closing the carrier after the inhibitor gas or inhibitor fluid is provided.

9. The method of claim 1, wherein the inhibitor gas or inhibitor fluid is provided with a low-pressure system.

10. The method of claim 1, wherein the interior of the carrier is only spot-treated with the inhibitor gas or inhibitor fluid.

11. The method of claim 1, wherein the vapor-phase corrosion inhibitors are provided in an amount sufficient to inhibit corrosion of the objects to be protected during a transportation and storage period.

12. A method of preparing at least one metal-containing object for transportation or storage comprising the steps of:

placing the object in a carrier;

closing the carrier loaded with the object and the inhibitor gas or inhibitor fluid, wherein the amount of vapor-phase corrosion inhibitors is adequate to ensure sufficient vapor-phase corrosion inhibitors are present to inhibit corrosion of the object to be protected.

13. The method of claim 12, wherein the at least one metal-containing object is selected from the group consisting of: camshafts, crankshafts, motor blocks and cylinder heads.

14. The method of claim 12, wherein the metal in the at least one metal-containing object is non-passivatable.

15. The method of claim 12, wherein the vapor-phase corrosion inhibitors are provided in an amount sufficient to inhibit corrosion of the objects to be protected during a transportation and storage period.