QC/T 942

QC/T 942-2013英文版/English/翻译

ChinaAutoRegs｜QC/T 942-2013英文版/English/翻译/汽车材料中六价铬的检测方法

Test Method for Hexavalent Chromium in Automobile Materials

QC/T 941-2013 英文版 汽车材料中汞的检测方法 Test methods of mercury in automobiles materials

QC/T 942-2013 英文版 汽车材料中六价铬的检测方法 Test Method for Hexavalent Chromium in Automobile Materials

QC/T 943-2013 英文版 汽车材料中铅、镉的检测方法 Test Method for Lead and Cadmium in Automobile Materials

QC/T 944-2013 英文版 汽车材料中多溴联苯（PBBs）和多溴二苯醚（PBDEs）的检测方法 Test Method for Poly-Brominated Biphenyls (PBBs) and Poly-Brominated Diphenyl Ethers (PBDEs) in Automobile Materials

1 SCOPE

This standard specifies the methods for determining the hexavalent chromium (Cr(VI)) content in automobile parts and materials, where,

"X-ray fluorescence spectrometry" is applicable to screening and rapid determination of Cr(VI) content in automobile materials by using X-ray fluorescence spectrometry.

"Qualitative test for the presence of hexavalent chromium in anti-corrosive metal coatings" is applicable to determining the presence of Cr(VI) in anti-corrosive coatings of automobiles by using spot-test procedure and boiling water extraction procedure. "Determination of hexavalent chromium content in anti-corrosive metal coatings" is applicable to determining the Cr(VI) content in anti-corrosive coatings by using boiling water extraction procedure and colorimetric method. The above two test methods are applicable to the coatings without any additional covering layer, e.g. oil film, water-based or solvent-based polymer film or waxy film.

"Determination of hexavalent chromium content in polymer materials and electronic materials" is applicable to determining the Cr(VI) content in polymers and electronics by using alkaline extraction method and colorimetric method, but not applicable to PE or EVAC material. The Cr(VI) content in other automobile materials, e.g. glass, ceramics, fabrics, and paint coatings, can be determined by reference to this method.

"Determination of hexavalent chromium content in leather materials" is applicable to determining the Cr(VI) content in leather materials by using phosphate solution extraction method and colorimetric method.

2 NORMATIVE REFERENCES

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 1839 Steel product zinc coating mass testing method (GB/T 1839-2008, ISO 1460:1992, MOD)

GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values

GB/T 20017 Metallic and Other Non-organic Coatings—Determination of Mass per Unit Area—Review of Gravimetric and Chemical Analysis Methods (GB/T 20017-2005, ISO 10111:2000, IDT)

GB/T 30512-2014 Requirements for Prohibited Substances on Automobiles

GB/Z 21277-2007 Rapid screening of lead, mercury, chromium, cadmium and bromine of regulated substances in electrical and electronic equipment - X-ray fluorescence spectrometry

QB/T 2262-1996 Terms for Leather Industry

QB/T 2706 Leather—Chemical, Physical and Mechanical and Fastness Tests—Sampling Location (QB/T 2706-2005, ISO 2418:2002, MOD)

IEC 62321:2008 Ed.1.0 Electrotechnical products—Determination of levels of six regulated substances (lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers)

ISO 3613:2000 Chromate Conversion Coatings on Zinc, Cadmium, Aluminium—Zinc Alloys and Zinc-Aluminium Alloys—Test Methods

EN ISO 17075:2007 Leather—Chemical Tests—Determination of Chromium (VI) Content

3 X 射线荧光光谱法

3. 1 原理

将制备好的样品置于X 射线荧光光谱仪样品室内， 按所选定的分析模式对样品中的铭含量进行X 射线荧光光谱分析，并根据筛选限值判断样品中铬含量是否合格， 以及是否需要进行精确测定。

注： x射线荧光光谱分析所得结果是样品所含的总路而非六价铬。

3.2 试剂和材料

3.2.1 棚酸：优级纯105 ℃烘1 h 储存于干燥器内。

3.2.2 无水囚棚酸鲤：优级纯， 700℃灼烧轴，储存于干燥器内。

3.2.3 液氮：工业级。

3.2.4 含铭元素的标准物质。

3.3 仪器和设备

3.3.1 X 射线荧光光谱仪。

3.3.2 切割机。

3.3.3 液氮低温粉碎机。

3.3.4 研磨机：带碳化鸽（ WC ）磨具。

3.3.5 压片机：工作压力不小于20MPa 0

3.3.6 熔样机：工作温度不低于1150 ℃ 。

3.4 样品制备

3. 4. 1 样品制备原则。

3. 4. 1. 1 用于分析的样品必须覆盖光谱仪的测量窗口。

3.4. 1.2 样品的照射面应能代表样品整体。

3.4. 1.3 样品制备过程中应注意防止污染。

3.4.2 样品制备方法。

3. 4.2. 1 固体样品。表面平整、大小适合X 射线荧光光谱仪要求的均质样品，直接分析。小样品可汇在一起进行分析。薄样品，可将其叠在一起达到足够厚（厚度至少5mm ），需特别注意样品厚度的一致性及组成的均匀性。分析时为使样品平整铺开，可加内衬材料作为支撑物，应尽量选用背景低的内衬材料。

各种块、板等不定形的样品以及尺寸过大的样品，可用切害IJ 机、研磨机等将其加工至合适尺寸。

小样品（如塑料颗粒等）通过液氮冷冻、机械粉碎再经压片机压片制成分析样品。

玻璃、陶瓷等易碎样品先粉碎成小块，再研磨成小于200 目（ 0. 074mm ）的粉末，混匀，用棚酸(3.2.1 ）衬底压片制样，厚度不小于1mm ，或用无水四棚酸鲤（ 3.2.2 ）制成玻璃融片分析样品。

由不均匀材料组成的、无需或难以进－步机械拆分的非均质样品，将样品切割破碎，经液氮冷冻，用研磨机将破碎后的样品研磨成粒径不超过1mm 的粉末状样品，混匀，用棚酸（ 3.2.1 ）衬底压片制样，厚度不小于1mm ，或用无水囚棚酸鲤（ 3.2.2 ）制成玻璃融片分析样品。

3.4.2.2 液体样品。移取一定体积的液体样品加入到液体专用样品杯里（样品厚度至少15mm),杯底部用6mm 厚的聚脂膜支撑， 杯上用带孔的盖盖住。