GB/T 39138.3-2020 in English
VALIDMethods for chemical analysis of gold nickel chromium iron silicon boron alloys—Part 3:Determination of chromium,iron,silicon and boron contents—Inductively coupled plasma atomic emission spectrometry
- Issued on:2020-10-11
- Implemented on:2021-09-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$97.00
《GB/T 39138.3-2020金镍铬铁硅硼合金化学分析方法 第3部分：铬、铁、硅、硼含量的测定 电感耦合等离子体原子发射光谱法》由TC243（全国有色金属标准化技术委员会）归口，TC243SC5（全国有色金属标准化技术委员会贵金属分会）执行，主管部门为中国有色金属工业协会。
Introduction
Technical background of the standard
As an important part of the precious metal alloy analysis technology system, this standard establishes a multi-element simultaneous detection scheme for the special composition characteristics of gold-nickel-chromium-iron-silicon-boron alloy. Compared with the traditional chemical titration and gravimetric method, ICP-AES technology realizes the rapid joint detection of four elements, and the analysis efficiency is improved by more than 300%.
Detailed explanation of the method principle
| Element | Dissolution system | Characteristic spectrum (nm) | Detection limit (μg/mL) |
|---|---|---|---|
| Cr | HCl+HNO₃ | 283.563 | 0.05 |
| Fe | HCl+HNO₃ | 259.939 | 0.03 |
| HCl+HNO₃+HF | 251.611 | 0.10 | |
| B | HCl+HNO₃ | 249.772 | 0.08 |
Key Operating Points
Sample treatment: The determination of silicon requires the use of a polytetrafluoroethylene container. The amount of hydrofluoric acid added is controlled at 5 drops (about 0.25mL). Excessive addition will lead to volatilization loss of silicon. The verification data of a laboratory showed that when the amount of HF added increased from 3 drops to 7 drops, the silicon recovery rate dropped from 98.5% to 89.2%.
Spectral calibration: The standard requires that the correlation coefficient of the working curve be ≥0.9995. In practical applications, it is recommended to use a 5-point calibration (including zero point). A quadratic curve fitting is required for chromium elements in the range of 4-7%.
Precision control requirements
Repeatability tests show that when the chromium content is 5.65%, the absolute difference allowed for parallel determination is ≤0.25%; when the iron content is 2.35%, the difference allowed is ≤0.11%. The laboratory comparison should meet the following requirements:
- Chromium (4-7%): relative allowable difference 0.3%
- Silicon (3-5%): relative allowable difference 0.3%
- Boron/Iron (1-5%): relative allowable difference 0.2%
Implementation suggestions
1. Plasma parameter optimization: It is recommended to maintain the RF power at 1.2-1.4kW, the observation height at 12-14mm, the cooling gas at 12L/min, and the auxiliary gas at 1.0L/min in the argon flow rate
2. Interference correction: The iron 259.939nm spectrum is easily interfered by the matrix, and the background correction points (259.900nm and 259.970nm) should be used for baseline subtraction
3. Quality control: Each batch of samples should be inserted into the GSB-04-3269-2015 standard material for verification, and the recovery rate should be controlled within the range of 95-105%
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