Hydrogen Charging of Aluminum using Friction in Water

Summary

In order to introduce high amounts of hydrogen in aluminum and aluminum alloys, a new method of hydrogen charging was developed, called the friction in water procedure.

Abstract

A new method of hydrogen charging of aluminum was developed by means of a friction in water (FW) procedure. This procedure can easily introduce high amounts of hydrogen into aluminum based on the chemical reaction between water and non-oxide coated aluminum.

Introduction

In general, aluminum base alloys have higher resistance to environmental hydrogen embrittlement than steel. The high resistance to hydrogen embrittlement of aluminum alloys is due to oxide films on the alloy surface blocking hydrogen entry. To evaluate and compare the high embrittlement sensitivity between aluminum alloys, hydrogen charging is usually performed prior to mechanical testing^{1,2,3,4,5,6,7,8}<....

Protocol

1. Material preparation

1. Use 1 mm thick plates made of an aluminum-magnesium-silicon alloy containing 1 mass% Mg and 0.8 mass% Si (Al-Mg-Si).
2. Make test pieces from the Al-Mg-Si alloy plates having a gauge length of 10 mm and width of 5 mm.
3. Anneal the test pieces at 520 ˚C for 1 h using an air furnace. Quench in water as a solution heat treatment.
4. Anneal the test pieces at 175 ˚C for 18 h as a peak aging heat treatment (T6-temper).
5. Polish the surface of the test pieces using silicon carbide emery paper (#2000) without water.
6. Measure the weight of the polished specimens to a precision of 0.0001 g usi....

Results

Hydrogen generation/absorption by the FW procedure
Figure 2 shows the hydrogen generation behavior during the FW procedure of Al-Mg-Si alloys containing different amounts of iron from 0.1 mass % to 0.7 mass %. The specimen continuously emitted a high amount of hydrogen when the stirrer started to rotate. This suggests that hydrogen was generated by a chemical reaction caused by the friction between the alloy surface and water. In addition, the pH value of the water durin.......

Discussion

One important aspect of the FW procedure is the attachment of the two specimens to the magnetic stirrer. Because the center of the stirrer bar becomes the non-friction zone, it is best to avoid the attachment of the specimens at the center of the stirrer bar.

Control of the rotation speed of the stirrer bar is also important. When the speed is more than 240 rpm, it becomes difficult to maintain the reaction vessel on the stage of the magnetic stirrer. When the FW procedure is carried out at hi.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Air furnace	GC	QC-1
Aluminum alloy plates	Kobe Steel		Al/1.0 mass% Mg/0.8 mass% Si
Electric balance	A&D	HR-200
Glass container			Custom made
Magnetic stirrer	CORNING	PC-410D
Optical Comparator	NIKON	V-12B
pH meter	Sato Tech	PH-230SDJ
Quartz tube			Custom made
Rotary polishing machine	IMT	IM-P2
Secondary electrom microscope	JOEL	JSM-5310LV
Sensor gas chromatograph	FIS Inc.	SGHA
Silicon carbide emery paper	IMT	531SR
Tensile testing machine	Toshin Kogyo	SERT-5000-C
Tubular furnace	Honma Riken		Custom made