I hate the way he's always slagging off his colleagues.

他老损他的同事，我看不惯。

《牛津词典》

It can be used for various aluminum alloys. Casting may be made immediately after degassing and slagging off.

用于各种铝合金，除气后迅速扒渣，即可浇铸。

youdao

This article mentions about the existing problems of the old slagging off machine in No. 3 steel-making factory of Shougang;

概述了首钢第三炼钢厂原用扒渣机存在的问题；

youdao

What I'm doing is not slagging off, I'm saying I'm looking for someone who can unite our party and who can lead our party with exciting new radical ideas and I believe that the person who can do that best is Iain Duncan Smith.

BBC: News | BREAKFAST WITH FROST | The former Conservative Chairman, Michael Ancram, told Breakfast with Frost that a Kenneth Clarke leadership victory risks tearing the Party apart

The conversation moved on to those intense days of war almost 15 years back and we did what any member of the journalist tribe does when gathering after many years apart - slagging off the louder mutual acquaintances and wondering what ever happened to the quiet ones.

BBC: A classic tale of a life made good in America