Meaning of 融着 in metal plating

Question

Context: production of a copper-plated stainless steel sheet (Ｃｕめっきステンレス鋼板)

What is the meaning of 融着 in the following sentence?

多重巻きパイプ造管時のロールとの摺動によるＣｕめっき層のはく離を抑制し、Ｃｕめっき層同士を加熱により融着させる際に起こる未融着部（ボイド）の発生を抑制することができるＣｕめっきステンレス鋼板を提供する。

I understand the meaning of the whole sentence except for 融着. Judging from the first kanji, it must have something to do with fusion, adhesion or bonding, but I can't find the exact meaning on any dictionary. Here's my translation attempt of the part in bold:

... prevent the appearance of 未融着 parts (voids) that occur when 融着させる the copper-plated layer by heating.

Could you also explain how to interpret that 同士? Thank you for your help!

EDIT: I don't know if this can be of any help, but later in the same document there is a table that shows the technical properties of the copper-plated stainless steel sheet with a value named ブレ一ジング模擬加熱後のボイド発生率.

Answer 1

Probably you are checking the patent of 多重巻きパイプ用Ｃｕめっきステンレス鋼板およびその製造方法 by 日新製鋼. I do not understand the whole detail of the patent for sure, but 融着{ゆうちゃく} should be related to 「セルフブレージング」: "self-brazing" since the background:「背景」of the patent says

『多重巻きパイプは、Ｃｕめっきを施した鋼帯を造管用ロールで巻き回してパイプ形状に造管し、還元性ガス雰囲気中でＣｕの融点以上に加熱することによってＣｕめっき層同士を融着するセルフブレージング（以下、ブレージング）を行うことで製造される。』

The other patent by 日新製鋼 has the image of manufacturing process of self-brazing.

It says 『１が冷延鋼板: Cold-formed steel、２が銅めっき層: The layer of copper-plated、３がセルフブレ−ジングにより形成された銅融着層: the copper-fluxed layer shaped by self-brazing』

So, copper should be fluid in the joining process. Therefore, I hope the verb "flux" is enough for this brazing:「ブレージング」process to say 「融着」.

All in all, I am not an expert of metal-working process and I hope someone else know more can confirm the interpretation.