GB/T 20624.2-2006 English PDF (GBT20624.2-2006)

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GB/T 20624.2-2006: Paints and varnishes -- Rapid-deformation (impact resistance) tests -- Part 2: Falling-weight test, small-area indenter
GB/T 20624.2-2006
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
G 51
GB/T 20624.2-2006 / ISO 6272-2.2002
Paints and Varnishes - Rapid-deformation
(Impact Resistance) Tests - Part 2. Falling-weight
Test, Small-area Indenter
色漆和清漆 快速变形(耐冲击性)试验
第 2部分. 落锤试验(小面积冲头)
(ISO 6272-2. 2002, IDT)
ISSUED ON. SEPTEMBER 1, 2006
IMPLEMENTED ON. FEBRUARY 1, 2007
Jointly Issued by. General Administration of Quality Supervision,
Inspection and Quarantine;
Standardization Administration of the People's
Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative References ... 4 
3 Term and Definition ... 5 
4 Required Supplementary Information ... 5 
5 Principle ... 5 
6 Significance and Use ... 5 
7 Apparatus ... 5 
8 Reagents ... 6 
9 Sampling ... 6 
10 Test Panels ... 6 
11 Conditioning ... 7 
12 Procedure... 7 
13 Precision ... 8 
14 Test Report ... 9 
Appendix A ... 10 
Bibliography ... 11 
Foreword
GB/T 20624 "Paints and Varnishes - Rapid-deformation (Impact Resistance) Tests -
Part 2. Falling-weight Test, Small-area Indenter" is divided into the following two parts.
— Part 1. Falling-weight Test, Large-area Indenter;
— Part 2. Falling-weight Test, Small-area Indenter.
This Part is the Part 2 of GB/T 20624.
This Part is identical to International Standard ISO 6272-2.2002 "Paints and Varnishes
- Rapid-deformation (Impact Resistance) Tests - Part 2. Falling-weight Test,
Small-area Indenter" (English edition).
Appendix A of this Part is normative.
This Part was proposed by China Petroleum and Chemical Industry Association.
This Part shall be under the jurisdiction of National Technical Committee on Coatings
and Pigments of Standardization Administration of China.
Drafting organization of this Part. Paint and Coatings Chemical Industry Research
Institute of CNCCC.
Chief drafting staff of this Part. Zhou Wenpei.
Paints and Varnishes - Rapid-deformation
(Impact Resistance) Tests - Part 2. Falling-weight
Test, Small-area Indenter
1 Scope
This Part of GB/T 20624 specifies a method for rapidly deforming, by using a
spherical indenter of diameter 12.7 mm or 15.9 mm to impact a coating film and its
substrate. And evaluate the effect of such deformation.
Note. The term “impact resistance” is included in the title and text of this Part, but one important
characteristic of the apparatus used is that it should produce rapid deformation rather than a true impact.
This test method should be restricted to testing in only one laboratory when numerical
values are used because of the poor reproducibility of the method. Interlaboratory
agreement is improved when ranking is used in place of numerical values.
2 Normative References
The following normative documents contain provisions which, through reference in
this text, constitute provisions of this Part of GB/T 20624. For dated references, the
subsequent amendments or revisions of these publications do not apply. However,
parties who enter into an agreement based on this Part are encouraged to investigate
the possibility of applying the most recent editions of the normative documents
indicated below. For undated references, the latest edition of the normative document
referred to applies.
GB/T 3186-2006 Paints Varnishes and Raw Materials for Paints and Varnishes -
Sampling (ISO 15528.2000, IDT)
GB/T 9271 Paints and Varnishes; Standard Panels for Testing (GB/T 9271-1988,
eqv ISO 1514.1984)
GB 9278 Temperatures and Humidities for Conditioning and Testing of Paint
Specimens (GB 9278-1988, eqv ISO 3270.1984 Paints and Varnishes and Their
Raw Materials - Temperatures and Humidities for Conditioning and Testing)
GB/T 13452.2 Paints and Varnishes - Determination of Film Thickness (GB/T
13452.2-1992, idt ISO 2808.1974)
ISO 1513 Paints and Varnishes - Examination and Preparation of Samples for
Testing
3 Term and Definition
For the purposes of this Part, the following term and definition apply.
3.1 Impact resistance of a coating
Number of kilogram-metres required to produce cracking in a deformed coating.
4 Required Supplementary Information
For any particular application, the test method specified in this Part needs to be
completed by supplementary information. The items of supplementary information are
given in Appendix A.
5 Principle
The coatings under test are applied to suitable thin metal panels. After the coatings
have cured, a standard weight is dropped a distance so as to strike an indenter that
deforms the coating and the substrate. The indentation can be either an intrusion or
an extrusion. By gradually increasing the distance the weight drops, the point at which
failure usually occurs can be determined. Films generally fail by cracking, which is
made more visible by the use of a magnifier, by the application of a copper sulfate
(CuSO4) solution on steel, or by the use of a pinhole detector.
6 Significance and Use
Coatings attached to substrates are subjected to damaging impacts during the
manufacture of articles and their use in service. In its use over many years, this test
method for impact resistance has been found to be useful in predicting the
performance of organic coatings for their ability to resist cracking caused by such
impacts.
7 Apparatus
7.1 Tester, consisting basically of a vertical tube to guide a cylindrical weight that is
dropped on a punch resting on the test panel, and including the components
described in 7.1.1 to 7.1.4.
7.1.1 Guide tube, 0.6 to 1.2 m long, mounted vertically in a base plate. A slot is cut
14 Test Report
The test report shall contain at least the following information.
a) All details necessary to identify the product tested;
b) A reference to this Part;
c) The items of supplementary information referred to in Appendix A;
d) A reference to the international or national standard, product specification or
other document supplying the information referred to in c);
e) The result of the test as indicated in Chapter 12, indicating the kilogram-metres
at the impact failure end point;
f) Whether intrusion or extrusion was used;
g) The diameter of the punch used;
h) Any deviation from the test method specified;
i) The date of the test.
Note. Because of the poor reproducibility of this method, the reporting of kilogram-metres in
comparing coatings for impact resistance should be restricted to one laboratory. For interlaboratory
comparisons, ranking of coatings for impact resistance should be reported.
Appendix A
(Normative)
Required Supplementary Information
The items of supplementary information listed in this Appendix shall be supplied as
appropriate to enable the method to be carried out.
The information required should preferably be agreed between the interested parties
and may be derived, in part or totally, from an international or national standard or
other document related to the product under test.
a) The thickness and surface preparation of the substrate.
b) The method of application of the test coating to the substrate, including
duration and conditions of drying between coats in the case of a multi-coat
system.
c) The duration and conditions of drying (or stoving) and ageing (if applicable) of
the coat before testing.
d) The atmospheric conditions under which the coated panels were conditioned,
the conditioning time and the atmospheric conditions under which the panels
were tested.
e) The thickness, in micrometres, of the dry coating and the method of
measurement used from GB/T 13452.2, and whether it is a single coat or a
multi-coat system.
f) The height, if appropriate, from which the weight is to be dropped.
g) Whether the weight is to fall onto the coated face of the test panel or onto the
opposite side, or both.