Knowledge

In a 90°C seawater cathodic protection system, titanium heaters are subject to both corrosive attack and hydrogen embrittlement. The weld toe is a region of high stress concentration. As-welded jo

In a 90°C seawater cathodic protection system, titanium heaters are subject to both corrosive attack and hydrogen embrittlement. The weld toe is a region of high stress concentration. As-welded jo

Grade 7 titanium contains 0.12–0.25% palladium, which is an efficient catalyst for hydrogen peroxide decomposition: 2H₂O₂ → 2H₂O + O₂. At 60°C, the initial decomposition rate is high, p

Post-weld pickling in a nitric-hydrofluoric acid mixture (HNO₃/HF) removes the oxygen-enriched alpha-case layer from titanium welds. A short pickle (5 minutes) removes 10–20 µm, leaving so

Sodium persulfate (Na₂S₂O₈) is a strong oxidizer (E° = 2.01 V for S₂O₈²⁻/SO₄²⁻), stronger than nitric acid. However, on titanium, persulfate causes transpassive dissolution rather than s

In 25% sodium hydroxide at 90°C, silica (SiO₂) reacts with titanium to form sodium titanate (Na₂TiO₃) and sodium silicate scales. These scales have very low thermal conductivity (0.5–1.5 W/m

In 30% sodium thiocyanate (NaSCN) at 80°C, thiocyanate anions (SCN⁻) adsorb strongly onto the titanium surface, forming a protective barrier. When chloride ions are present, SCN⁻ competes for surf

In 3% NaCl at 80°C, titanium exhibits characteristic electrochemical noise before pitting. Metastable pits produce short, low-amplitude current spikes (0.1–1 µA, duration 0.1–1 s

In 20% sodium bicarbonate (NaHCO₃) slurry at 60°C, bicarbonate crystals precipitate as the solution is heated. These crystals have a Mohs hardness of 2.5–3.0, which is less than titanium'

In 5% sodium tripolyphosphate (STPP) at 90°C, calcium ions precipitate as calcium phosphate (Ca₃(PO₄)₂) scale. This scale has low thermal conductivity (0.3–0.6 W/m·K). The maximum all

In a mixture of hydrofluoric (HF) and nitric (HNO₃) acids, the ratio of HNO₃ to HF determines the corrosion morphology. At a low ratio (2:1, e.g., 1% HF + 2% HNO₃), pitting dominates due to incomplete

In sodium metasilicate (Na₂SiO₃) solutions at 80°C, silicate ions polymerize on titanium surfaces. At pH >11, the silicate forms a continuous, non-porous, protective film (thickness 0.5–2