DE10010252A1 - Test chamber used as a salt mist chamber or moisture chamber for corrosion tests on cars has an inner surface with a plastic coating with a specified breaking elongation - Google Patents

Abstract

Test chamber (5) has an inner surface with a plastic coating (1) whose breaking elongation is more than 150, especially more than 250 %. Preferred Features: The walls, ceiling and/or base of the chamber contain concrete blocks (4) and an insulating foam core (3).

Description

The invention relates to a test chamber, in particular a salt spray chamber or a Moisture chamber for corrosion tests on automobiles.

It is known to assess the corrosion resistance of automotive prototypes Test vehicle for a defined period in a test chamber with a defined, exposure to a stressful atmosphere. This can be, in particular act saline fog in a so-called salt fog chamber. The salt spray typically contains about 5 percent by weight of salt (NaCl), which at Room temperature into the chamber at a rate of descent of about 1 to 2 mm per hour is introduced. So-called moisture chambers are also in use, the one Contain atmosphere with increased humidity and warmth. Typical values for these parameters are 95% relative humidity and 50 ° C.

Due to the corrosive atmospheres, the sealing of the above mentioned Test chambers represent a particular problem. According to the state of the art, the Sealing with a lining of the inner walls of the test chamber Stainless steel plates or glass fiber reinforced plastic. Has a stainless steel cladding however, the disadvantage of being very expensive. On the one hand, this applies to the material costs others, however, the installation of such a panel is very expensive. Around To build a watertight chamber, every seam must be carefully sealed. The The best possible seal is achieved by welding the stainless steel plates, which is very time consuming and therefore costly. Will the stainless steel plates on the other hand, provided with other sealing seams, this requires constant checks and maintenance to maintain the tightness of the seam. Furthermore, the Stainless steel will start to corrode one day, which will add extra effort to the Maintenance and repair required. In contrast, panels are with Glass fiber reinforced plastic is less expensive than stainless steel, but it does require significantly more maintenance and repairs. The test chamber is because of the Temperature changes of a constant expansion and contraction taking place there subjected, which causes cracks in the glass fiber reinforced cladding. Such  Microscopic cracks and large cracks on the seams therefore have to be repaired constantly become. If the cladding leaks at one point, the wall is saturated and the ceiling insulation with moisture.

The object of the present invention was to provide a test chamber, which are less expensive to manufacture and maintain than the known ones Test chambers is. In particular, the test chamber should be a salt spray chamber or Moisture chamber may be suitable for corrosion tests.

This object is achieved according to claim 1 by a test chamber in which at least part of the inner surface with a coating of a plastic is provided, the elongation at break of which is greater than 150%, preferably greater than 250% is. This means that the plastic coating is stretched by at least 1.5 endures at least 2.5 times its original length, without tearing. Such a plastic coating can be proportionate Apply inexpensively to the inner wall of a salt spray chamber. Due to the The required stretch properties are also kept under the permanent Temperature changes and the associated expansion movements their tightness because it can follow such stretches without breaking. A constant elaborate Maintenance of the plastic coating is therefore generally not necessary. The entire inner wall of the test chamber is preferably covered with one Provide plastic coating. The advantages of the invention occur in one the corresponding extent, of course, if only a part of the Wall is coated with plastic.

For the sealing of the test chamber is in particular one according to claim 2 Suitable for polyurethane coating. Polyurethanes are created by polyaddition of Diols (HO-R-OH) with diisocyanates (O = C = N-R'-N = C = O) with training the urethane bond (R-O-CO-NH-R '). You can expand by 300% without having to break. The said polyurethane coating is preferably made from a so-called two-component system, in which shortly before the Processing a hardener (reactive polyisocyanates) with a paint component (Polyhydroxyl compound) is mixed, whereupon the polymerization which then begins leads to hardening of the paint. A polyurethane coating can in particular be sprayed onto the walls of the test chamber. This forms  a continuous and seamless waterproof barrier that will not break expands and contracts under the temperature changes taking place. The Investment costs for a polyurethane coating are comparatively very low. Maintenance of the coating is practically not necessary. The coating is enough to keep clean by spraying with water. Occasionally, she can also use a mild soap and water. The polyurethane coating is for Moisture and salt spray impenetrable and does not corrode and decompose a salt spray atmosphere. Should it ever damage the Coming through, the polyurethane coating can pass through easily and quickly Painting can be repaired.

The plastic coating applied to the inner walls of the test chamber has been left behind Claim 3 a thickness of 0.5 to 20 mm, preferably 1 to 15 mm, particularly preferably 2 to 10 mm. The layer thicknesses mentioned are optimal Compromise of tightness of the coating and reduction of material costs represents.

A development of the invention according to claim 4 relates to an advantageous structure of the Walls and / or the ceiling and / or the bottom of the salt spray chamber. Accordingly these elements contain concrete blocks with an insulation core. Such blocks on the one hand have the necessary stability for the production of wall, floor or Ceiling surfaces, on the other hand, the insulation core ensures that the manufactured with it Surface has a high thermal insulation capacity. Furthermore, the two-piece construction reduces the average specific weight of the stones, so this can be manufactured and processed in larger dimensions. Typically the concrete blocks have dimensions of 20 x 20 x 40 cm (8 "x 8" x 16 "). Advantageously, there is not only one part, but an entire wall or all Walls and / or the entire ceiling and / or the entire floor from the above Concrete blocks.

The insulation core of the concrete blocks can preferably be made of one Insulating foam is formed in the cavity of the block during manufacture is injected. For example, polyurethane foams (PUR) are suitable for this.  

A further advantageous construction for the walls and / or for the ceiling and / or the bottom of the test chamber consists according to claim 6 in a plywood layer with a suitable thermal insulation. Such a plywood layer is preferably provided with insulation for the ceiling of the test chamber. Typically, its thickness is 10 to 30 mm, preferably 15 to 25 mm (3/4 "). Preferably, plywood vessel (marine plywood) and a R-30 used Batt insulation.

In the following the invention is explained by way of example with the aid of a figure.

The figure shows a section of part of the wall and the ceiling of a salt spray chamber. During a test, a fog atmosphere with a 5% saline solution is generated in the interior 5 of the salt spray chamber. A sink rate of 1 to 2 mm per hour is typically set. Due to the high corrosiveness of the salt spray atmosphere and the frequent temperature changes within the salt spray chamber, the sealing of the inner walls is a particular problem. Seals made of stainless steel or glass fiber reinforced plastics known from the prior art have the disadvantage that they entail high installation and maintenance costs bring oneself.

In contrast, according to the invention, a considerably less expensive and simpler construction and sealing of the walls, the ceiling and the bottom of the salt spray chamber is achieved by providing the inner walls with a continuous plastic layer 1 , which has an elongation at break so high that it expands and contracts does not tear. The plastic layer 1 preferably consists of a polyurethane resin.

The walls of the salt spray chamber are preferably made of concrete blocks 4 , which have a hollow core. An insulation foam 3 is injected into this core, which ensures good thermal insulation of the wall produced.

In the ceiling region, the inside is preferably formed of a plywood layer 2, which typically has a thickness of about 20 mm (3/4 ") and is (not shown) with a further insulating layer for thermal insulation provided.

Typical dimensions of a salt spray chamber are 10.4 × 4.7 × 3.5 m (length × width × height) with a roof pitch of 30 °, corresponding to a ridge height of 4.9 m. This results in a volume of the salt spray chamber of approx. 170.6 m ³ .

After the shell has been manufactured, the inner walls of the salt spray chamber are sprayed with a two-component polyurethane paint. This creates a continuous, seamless and watertight barrier 1 which takes part in the contractions and expansions taking place in the chamber due to the temperature changes without tearing. Polyurethane is particularly preferred because it allows 300% expansion.

The advantages of a salt spray chamber according to the invention are that the Interior coating is very cheap from the material and manufacturing costs. In addition, there are virtually no maintenance costs, as an occasional washing up the walls with water or soap are sufficient. Otherwise, the polyurethane Coating resistant to the salt spray. Should the layer be damaged exhibit (for example, by mechanical effects), so it can be easier Can be repaired again by painting over. Thus, the lie Operating costs for a salt spray chamber produced according to the invention on a very low level.

The above statements also apply in a similar form to a typical humidity chamber. However, the ceiling is preferably a flat roof made of prefabricated I-beams, which are covered by 25 mm (1 inch) plywood (ship quality). The ceiling and walls are spray-coated with a polyurethane coating (for example, SWD 951 polyurethane elastomer coating from the SWD Urethane Company in Mesa Arizona, USA). The floor is preferably made of cement and coated with a two-component epoxy resin (for example Duraltex from Dural Polymers). All joints are sealed with a corrosion-resistant material. The doors of the chambers are preferably made of stainless steel.

REFERENCE SIGN LIST

1

Coating

2

Plywood layer

3rd

Insulating foam

4

Concrete block

5

Test chamber

Claims (6)

1. test chamber ( 5 ), in particular salt spray chamber or moisture chamber for corrosion tests, characterized in that at least part of the inner surface of the test chamber is provided with a coating ( 1 ) made of a plastic, the elongation at break of which is greater than 150%, preferably greater than 250% . 2. Test chamber according to claim 1, characterized in that the coating ( 1 ) contains a polyurethane. 3. Test chamber according to one of claims 1 or 2, characterized in that the coating ( 1 ) is 0.5 to 20 mm, preferably 1 to 15 mm, particularly preferably 2 to 10 mm thick. 4. Test chamber according to one of claims 1 to 3, characterized in that the walls and / or the ceiling and / or the bottom of the test chamber contain concrete blocks ( 4 ) with an insulation core ( 3 ). 5. Test chamber according to claim 4, characterized in that the insulation core is formed from an insulating foam ( 3 ). 6. Test chamber according to one of claims 1 to 5, characterized in that the walls and / or the ceiling and / or the bottom of the test chamber contain a plywood layer ( 2 ) and thermal insulation.