Hydrogels, especially Polyvinyl alcohols, have received extensive attention as alternative materials for articular cartilage. Aiming at the problems such as low strength and poor toughness of polyvinyl alcohol hydrogels in practical applications, an enhancement and modification strategy is proposed. Sodium alginate fibers were introduced into polyvinyl alcohol hydrogel network through physical blending and freezing/thawing methods. The prepared composite hydrogels exhibited a three-dimensional porous network structure similar to that of human articular cartilage. The mechanical and tribological properties of hydrogels have been significantly improved, due to the multiple hydrogen bonding interaction between sodium alginate fibers and polyvinyl alcohol. Most importantly, under a load of 2 N, the friction coefficient of the PVA/0.4SA hydrogel can remain stable at 0.02 when lubricated in PBS buffer for 1 h. This work provides a novel design strategy for the development of high-performance polyvinyl alcohol hydrogels.

Effects of Nb on the creep resistance and hot corrosion behavior of the Fe-25Cr-35Ni-2.5Al-xNb (x = 0, 0.6, 1.2) Alumina-Forming Austenitic stainless steels (AFA steels) at 700 °C were investigated. The addition of Nb promoted the precipitation of both nanoscale NbC and γ′-Ni₃(Al, Nb) phases, which exhibited very low coarsening rate constants. The nanoscale NbC and γ′-Ni₃(Al, Nb) phases effectively impeded the migration of dislocations and led to an improvement in creep performance of the Nb-addition AFA steel. The corrosion of AFA steels in Na₂SO₄-25%K₂SO₄ at 700 °C was primarily driven by an “oxidation-sulfidation” mechanism. The addition of Nb, serving as a third element, facilitated the formation of protective Cr₂O₃ and Al₂O₃ films, which improved the hot corrosion resistance performance. However, the formation Nb₂O₅ was found to compromise the compactness of the oxide film, which adversely affected the corrosion resistance.