Table 2.

Summary of investigations without or not specified designed experiments.

Deposition Technology	Input Variables	Responses	Method	Reference
PTAW	Content of sand; Slurry temperature; Velocity of slurry	Mass loss (erosion-corrosion)	Curve fitting	[40]
PTAW LC	Average distance between WC particles; Average diameter of WC particles; Volume fraction of WC particles; Matrix hardness; Shape of WC particles	Wear rate (continuous impact abrasive wear)	Regression model	[41]
LC	Volume removed (worn); Load; Sliding speed	Mass loss (dry sliding wear–block on ring); Average wear rate	Curve fitting	[42]
	Weight % of WC	Wear track cross section (dry sliding wear–ball on disc)	Curve fitting	[43]
	Average distance between WC particles; Average diameter of WC particles; Volume fraction of WC particles; Matrix hardness	Wear rate (three-body abrasive wear)	Regression model	[44]
	Weight % of WC	Hardness; Intensity (laser-induced breakdown spectroscopy)	Curve fitting	[45]
	Pressure of carrier gas (air), Flow of carrier gas (air); Cladding distance, Laser spot speed	Powder feed rate; Clad height and width	Regression model	[46]
	Exposure time in salt fog	Weibull modulus (Knoop hardness distribution)	Weibull distribution	[47]
	-	-	Descriptive statistics	[48]
FS	Volume removed (worn)	Mass loss (dry sliding wear–block on ring)	Curve fitting	[49]
	Wear time	Wear volume (dry sliding wear–pin on disc)	Curve fitting	[50]
	Debris particle (Al2O3) size; Initial (or final) surface roughness, lubricant viscosity, sliding speed, contact pressure	Surface roughness; Coefficient of friction	Curve fitting	[51]
PS	Load	Frictional force (dry sliding reciprocating wear)	Confidence interval; Curve fitting	[52]
	Capacitance arc radius (Nyquist plot); Frequency (Bode impedance and phase plots)	Solution, film and charge transfer resistance; Capacity element; Warburg impedance; Constant phase element	Curve fitting; Chi-square test	[53]
	Linear parameters of pores	Spatial (3D) parameters of pores	Regression model; Correlation analysis	[54]
	Hydrogen flow rate	Porosity	Weibull distribution	[55]
	Power	Porosity	Weibull distribution	[56]
	Power	Porosity; Modulus of elasticity; Microhardness; Residual stress	Weibull distribution	[57]
	Powder feed rate	Porosity; Modulus of elasticity; Microhardness; Residual stress	Weibull distribution	[58]
	Hydrogen flow rate; Power; Powder feed rate	Porosity; Modulus of elasticity; Microhardness	Weibull distribution	[59]
	Contact pressure; Number of fatigue cycles	Failure probability	Weibull distribution	[60,61]
HVOF	Volume fraction of unmelted particles; sin2ψ (XRD measurement); Penetration depth	Surface roughness Rz; Interplanar spacing; Indentation load	Curve fitting	[62]
HVOF FS	Volume fraction of hard particles	Abrasive wear resistance (three-body abrasive wear)	Curve fitting	[63]
	-	-	Descriptive statistics	[64]
HVOF FS PS	-	-	Statistical distribution	[65]

PTAW—plasma-transferred arc welding; LC—laser cladding; FS—flame spraying; PS—plasma spraying; HVOF—high-velocity oxy fuel spraying.