High-Temperature Degradation and Protection of Ferritic and Austenitic Steels in Steam Generators

Abstract

The useful life of superheaters and reheaters of power stations which use heavy fuel oil is shortened and their continuous service is inhibited by corrosion (fireside) and creep-type problems. The increase of corrosion attack on boilers is caused by the presence of fuel ash deposits containing mainly vanadium, sodium, and sulfur which form low-melting-point compounds. The tubes are exposed to the action of high stresses and high temperatures, producing the so-called "creep damage." In this work, two kinds of results are reported: lab and field studies using a 2.25Cr-1Mo steel. The laboratory work was in turn divided into two parts. In the first, the steel was exposed to the action of natural ash deposits in oxidant atmospheres at 600 °C for 24 h. In the second part, tensile specimens were creep tested in Na 2 SO 4 , V 2 O 5 , and their mixture over a temperature range of 580 to 620 °C. In the field work, components of a power station were coated with different types of nickel-and iron-base coatings containing chromium, Fe-Cr, and Fe-Si using the powder flame spraying technique. After testing, the coated tubes were analyzed using electron microscopy. The results showed that all the coating systems had good corrosion resistance, especially those containing silicon or chromium.

A Comparative Study of Corrosion AA6061 and AlSi10Mg Alloys Produced by Extruded and Additive Manufacturing

“…It is important to separate the DC signal from the aforementioned variables to analyze the EN data. The corrosion data, presented at low frequencies, were conserved [ 27 , 28 , 33 , 41 , 42 , 43 , 44 ].…”

Delamination and Tensile Effect of Fine z-Binder Reinforced on Fiberglass/Polyester Composite for Aerospace Applications

“…This is mainly because such composites' manufacturing may generate resin-rich zones that can fracture prematurely and start different fracture mechanisms that depend on z-binder configuration and nature. Even though, due to their promising properties, 3D composites are of great interest for replacing metals applications, with different advantages such as corrosion resistance [52][53][54][55][56]. This motivates the generation of novel manufacturing processes such as the one presented in this study, a zigzagoriented z-binder [57], or even a 2.5D pattern composite [58].…”

Citric Acid as an Alternative to Sulfuric Acid for Hard Anodizing in Aluminum Alloys Used in the Aeronautical Industry

“…CPP with a potential sweep of -0.3 to 1.0 V against the saturated calomel electrode (SCE) was measured using one complete polarization cycle at a scan rate of 0.06 V/min. Following the norm ASTM G61-11 [22][23][24][25][26][27].…”