Works on coatings development for biomass boiler.

Deposition method	Material	Key finding	Ref.
HVOF	Inconel 625	A lower amount of Cr and Ni and a high amount of Fe may decrease corrosion resistance	107
	Inconel 718
Electric arc spraying	Fe–Cr–Mo amorphous coating + sodium silicate sealant	Cl acted as a catalyst for accelerating corrosion, and Fe and Cr were mainly chlorinated	108
Air plasma spraying (APS)	Ni–Al (Al = 5 wt%, Ni = balance) + preoxidation at 700 °C for 6 h	The porosity produces poor corrosion resistance, and pre-oxidation can hinder the ingression of corrosive species	109
HVOF	Stellite-6	Adequate protection by Cr2O3 outer layer and the sub-layer rich in Co (CoCr2O4 and CoO) resulted from the Stellite-6 coating. While NiAl coating severely damaged due to a chlorine attack	110
	NiAl
Electroplating + pack aluminizing	Ni	Nickel aluminide coating was corroded and formed AlCl3	111
	Ni2Al3
HVOF	Ni5Al	Cr oxides were blocking inter-splat corrosion attack, thus mitigating internal corrosion	112
	Fe50Cr
	Ni20Cr
HVAF	Ni21Cr9Mo	SiO2 induces the rapid formation of dense and highly attached Cr2O3 that hinders chloride diffusion	113
	SiO2-containing Ni21Cr9Mo
HVAF	Ni21Cr7Al1Y	Chloride reacted with Cr and Al to form CrCl3 and AlCl3 at the splat boundaries, while Mo can support the formation of a protective Cr oxide scale	114
	SiO2-containing Ni21Cr9Mo
Electroplating + pack aluminizing	Ni	Cl species was diffuse and propagated the corrosion reaction	115
	Ni2Al3
HVOF	NiAl	Inhibiting the diffusion of Cl2 and O2 is crucial because Cl2 acts as a catalyst, inducing the formation of NiCl2, AlCl3, and subsequent oxidation at the interface	116
HVAF	NiCr (in wt%; 78.6 Ni–21.3 Cr–0.1 O)	Cl− may diffuse and form metal chlorides through defects and splat boundaries. Moreover, Al2O3 was found to impede the Cl− diffusion	117
	NiAl (in wt%; 94.1 Ni–5.7 Al–0.2 O)
HVAF	Ni5Al	Al-rich oxide was observed to have better protection against KCl. Cr-rich oxide was prone to degradation due to chromate formation	118
	Ni21Cr
	Ni21Cr7Al1Y
	Ni21Cr9Mo