Meaning of 融着 in metal plating


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.




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](https://astamuse.com/ja/published/JP/No/2017150050)
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](https://en.wikipedia.org/wiki/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](https://astamuse.com/ja/published/JP/No/1994108284) 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**](https://en.wikipedia.org/wiki/Flux_\(metallurgy\)) 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」.

[![enter image description
here](https://i.stack.imgur.com/aMYbC.png)](https://i.stack.imgur.com/aMYbC.png)

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

