Impact of infrared radiation on oxide layer of ultrathin TiNi-based alloy wire
Advanced Materials Letters,
2018, Volume 9, Issue 10, Pages 715-720
AbstractDespite the well-known advantages of TiNi-based alloys, the cost of production is still high. The alloys are traditionally made by vacuum induction melting technology followed by vacuum arc remelting to get ingots which are further worked mechanically to final or semi-finished items. The special attention is paid by a thin wire which can be used as a suture material or for a tissue grafting. Thin TiNi yarns are produced by cold drawing via dies with the intermediate annealing. When a diameter is about or over 1 mm, the existing solutions give clear insight into a general idea about how to change the structure and properties of the alloy. However, when the size is definitely scaled-down to 90 μm and less, serious difficulties appear because such yarn requires thoroughly care in mechanical processing steps and repeated heat treatment increases the expense making the product costly and unprofitable. As working steps and heat treatment of the ultrathin TiNi-based wire (UW) are to be more predictable and controllable, there was suggested an infrared (IR) drawing heater due to the radial warming system located prior to the die. In hope to provide a more comprehensive understanding of this issue, a study on how the IR heating method influences on surface properties of the UW, comparing the various effects of heat treatment was carried out using the designed IR heater. The study covers the effect of oxide layer composition and its modification on the properties of the wire IR-heat drawn. Strong correlations were observed between oxide layer thickness and strength characteristic of the resultant wire. These findings elucidate the role of the oxide layer and its composition on a quality of the UW drawing process.
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