RU1779983C - Specimen for determining cohesive strength of coating with baking - Google Patents

Abstract

The invention relates to a test technique for determining the adhesion strength of coatings to a substrate. The aim of the invention is to expand the range of coatings studied in the difficult stress state. The sample consists of a cylindrical substrate located on its end surface coaxially with the annular plate deposited on the end surface of the substrate and the coating plate and glued to it by its end surface of the cylindrical tear-off element. Moreover, the thickness of the plate is less than the thickness of the coating, and its inner diameter is equal to the diameter of the substrate. 2 ill.

Description

The invention relates to a test technique for determining the adhesion strength of coatings to a substrate.

A known sample for determining the adhesion strength of a coating to a substrate, which consists of a substrate with an aperture mounted flush with the surface of the pin substrate, applied to their end surface of the coating and attached to the coating using the adhesive layer of the plate, Adhesion strength is judged by the value of the breaking load applied to the pin and the substrate

A drawback of the sample is the impossibility of testing the adhesion strength of the coating under difficult stress conditions and the narrow range of coatings that can be tested using a given adhesive.

The closest in technical essence to the claimed is a sample for determining the adhesion strength of the coating to the substrate, consisting of a cylindrical substrate deposited on its end surface of the coating and a cylindrical tear-off element glued with its end surface to the coating coaxially to the substrate.

A drawback of the sample is the impossibility of expanding the range of coatings studied under the difficult stress state, the adhesion strength of which is higher than the adhesive bond strength.

The aim of the invention is to expand the range of subjects under study VI VI

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00 GO

the stressed state of the coatings when using the specified adhesive.

The goal is achieved in that the sample for determining the adhesion strength of the coating to the substrate, consisting of a cylindrical substrate deposited on its end surface of the coating and a cylindrical tear-off element glued with its end surface to the coating coaxially to the substrate, is provided with an annular plate located on the end surface of the substrate coaxial with it, the inner diameter of which is equal to the diameter of the substrate, and the thickness does not exceed the thickness of the coating, which is also applied to the surface of the plate, and with the ratio of the diameters of the substrate and the tear element is selected from the condition

/ sp / b

O) (2)

DI and D2, respectively, the diameters of the substrate and the tear-off element;

o, TI are the adhesive strength values of the coating with the substrate, respectively, for separation and shear;

og, Z2 - adhesive strength of the tear-off element with the coating material, respectively, by tear and shear.

As the results of the patent search showed, there is no known sample for determining the adhesion strength of a coating in a difficult stress state, consisting of a cylindrical substrate deposited on its end surface of the coating and a cylindrical tear-off element glued with its end surface to the coating coaxially to the substrate, and which would be provided with an annular plate located on the end surface of the substrate coaxially with it, the inner diameter of which is equal to the diameter of the substrate, and the thickness does not exceed the thickness of the coating, which is also applied to the surface of the plate, and the ratio of the diameters of the substrate and the tear-off element would satisfy the conditions

0). (2).

A sample for determining the adhesion strength of a coating to a substrate in a difficult stress state is illustrated in the accompanying drawings.

Figure 1 shows a diagram of the proposed sample assembly in its manufacture; Fig. 2 is a diagram of loading a sample.

The sample consists of a cylindrical substrate 1, an annular plate 2 located on the end surface of the substrate 1 coaxially with it, the inner diameter

which is equal to the diameter of the substrate 1, and the thickness does not exceed the thickness of the coating 3, which is deposited on the end surface of the cylindrical substrate 1 and the annular plate 2, a cylindrical tear-off

element 4 attached with its end surface using an adhesive layer 5 to the coating 3 coaxially to the substrate 1. In order to install the annular plate 2, its back side in the same plane with the end face

the surface of the cylindrical substrate 1, and increase its rigidity during the coating process 3, the annular plate 2 is supported by a ferrule 6 on the cylindrical substrate 1. Before testing

clip 6 is removed. During the tests, normal tear or compressive forces and shear forces are applied to the cylindrical substrate 1 and the cylindrical tear-off element 4, the magnitude of which determines

adhesion strength of the coating to the substrate (Fig. 2).

In order for the coating to peel off from the end face of the cylindrical substrate 1 without destroying the adhesive joint 5, the diameters of the cylindrical substrate 1 and the cylindrical tear-off element 4 must satisfy the condition

35

Di d2

(3)

under normal force and condition

 )

under the action of shear. From these conditions the relations (1), (2) follow. To ensure guaranteed separation of coatings while applying

For normal and shear forces, a ratio of diameters greater than a larger value should be selected from those obtained under conditions (3) and (4).

For example, when tested for strength

adhesion in the difficult stress state of the coating of PG-19M-01 material on pre-spec-steel samples of steel using BC-350 glue, we have

a 1 22.0 MPa; g i 30.0 MPa

about 2 14.0 MPa; G2 17.3 MPa

With DI 10 mm, D2 12.5 mm by condition (3) and D2 13.1 mm by condition (4). Diameter

The tear-off element of the sample should be taken more than 13.1 mm.

When testing the adhesion strength of a NiCr coating on pre-spliced steel 5

8MPa; p-75.0MPa

With D-, 10 mm, D2 16.0 mm by condition (3) and D2 20.8 mm by condition (4). The diameter of the tear-off element of the sample should be taken more than 20.8 mm.

The advantage of the proposed sample for determining the adhesion strength of a coating to a substrate is that it allows expanding the assortment of the coatings being studied under the difficult stress state using a given adhesive, which means reducing labor costs and costs when testing various coatings.

Claims (1)

The claims A sample for determining the adhesion strength of a coating to a substrate, consisting of a cylindrical substrate deposited on its end surface of the coating and a cylindrical tear-off element glued with its end face. surface to the coating coaxially with the substrate, characterized in that. what. in order to expand the range of coatings studied under difficult stress conditions, the sample is equipped with an annular plate located on the end surface of the substrate coaxially with it, whose inner diameter is equal to the diameter of the substrate, and the thickness does not exceed the thickness of the coating, which is also applied to the surface of the plate, and the ratio of the separation diameter D2 to the diameter DI of the substrate is selected from the condition D2 / Di K, Where g / 1, p values of the adhesive strength of the coating with the substrate, respectively, for separation and shear; Ojz. G2 is the adhesive strength of the tear-off element with the coating material, respectively, for tear and shear. / V I I F N V