HVOF-Deposited WCCoCr as Replacement for Hard Cr in Landing Gear Actuators

WCCoCr coatings deposited by HVOF can replace hard Cr on landing gear components. Powders with two different WC particle sizes (micro and nano-) and geometries have been employed to study the effects on the coating’s properties. Moreover, coatings produced employing two sets of parameters resulting in high and low flame temperatures have been evaluated. Minor differences in microstructure and morphology were observed for the two powders employing the same spraying parameters, but the nano-sized powder exhibited a higher spraying efficiency. However, more significant microstructural changes result when the low- and high-energy spray parameters are used. Moreover, results of various tests which include adhesion, wear, salt fog corrosion resistance, liquid immersion, and axial fatigue strength, indicate that the coatings produced with high-energy flame are similar in behavior. On the other hand, the nanostructured low-energy flame coating exhibited a significantly lower salt fog corrosion resistanc

Electrochemical imaging for the pitting initiation of 18/8 stainless steel

The micro and nano electrochemical imaging techniques of scanning micro reference electrode and electrochemical scanning tunneling microscope were employed to study the pitting corrosion in an early stage of 18/8 stainless steel in chloride containing solution. A critical potential E-r measured by the potential imaging was used to characterize the local rupture of passivity and micropitting initiation. The concept of metastable micro pitting was adopted to discuss the mechanism of pitting corrosion at its early stage

A study of Al-Mo powder processing as a possible way to corrosion resistent aluminum-alloys

Elementary Al and Mo powder mixtures have been processed by high energy ball milling up to milling times of 100 hours. The shift of the pitting potential and the X ray analysis of green milled samples showed that part of the Mo has formed a supersaturated solid solution of Mo in Al. Elementary Mo powder, however, was still present after 100 hours of milling. Sintering led to the formation of the intermetallic Al12Mo phase

Investigation of Pitting Corrosion in Sensitized Modified High-Nitrogen 316LN Steel After Neutron Irradiation

The influence has been studied of thermo-mechanical treatment, sensitization conditions, and neutron irradiation on the pitting corrosion resistance of austenitic 316LN stainless steel variants in 10% FeCl[subscript 3]·6H[subscript 2]O at 22 °C. Variants of this steel were modified with additions of nitrogen, manganese, copper, and tungsten, as well as testing cast, cold-rolled, grain boundary engineered (GBE), and as-received variants. It was found that the 316LN steel variant with additions of 0.2% N and 2% Mn had the best pitting corrosion resistance of all studied conditions. When irradiated in a light water reactor (LWR) to a maximum fluence of 3 × 1017 n/cm[superscript 2] (E > 1.1 meV, Tirr < 50 °C), neutron irradiation surprisingly increased the resistance of GBE steels to pitting corrosion. An anisotropy of corrosion resistance of GBE and cold rolled steels was observed. Keywords: Austenitic stainless steel, Alloying, Nitrogen, Tungsten, Copper, Sensitization, Pitting corrosion, Grain boundary engineerin