Among them, pack cementation,
which is based on the CVD process, is considered to be an
effective surface treatment to improve the corrosion resistance of
steel bipolar plates since it produces a uniform diffuse layer on the
steel surface and maintains high coherence at the interface between
the diffuse layer and the substrate [12–14].
我想請問一下 這段話裡的pack cementation, 是指什麼意思?