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This paper proposes an overlay coating based on the high-entropy alloy composition NiCo 0.6 Fe 0.2 Cr 1.5 SiAlTi 0.2 [high-entropy alloy coating (HEAC)]. HEAC samples underwent spark-plasma sintering processes and were subjected to oxidation tests, hightemperature hardness tests, and thermal conductivity and thermal expansion measurements. Experimental results indicated that the HEAC can form protective α-Al 2 O 3 at 1100 • C and exhibits oxidation behavior similar to that of MCrAlY. Furthermore, compared to MCrAlY, the HEAC possesses better thermal stability, higher hot hardness, lower thermal conductivity, and smaller thermal expansion. The potential of the HEAC as an overlay coating for high-temperature applications is discussed.

Atmospheric plasma spraying, high-velocity oxy-fuel spraying and warm spraying processes were used to prepare NiCo 0.6 Fe 0.2 Cr 1.5 SiAlTi 0.2 and NiCo 0.6 Fe 0.2 Cr 1.3 SiAl high-entropy alloy coatings for the investigation of their high temperature properties. The best-performer, the warm-sprayed high-entropy alloy coating was then applied to a thermal barrier coating system as a bond coat over an Incoloy 800H substrate. Experimental results show that the investigated high-entropy alloy coatings have high hardness, excellent wear resistance and good oxidation resistance at 1100 • C that makes them promising overlay coatings for elevated temperature applications.

Background: Osteoporotic spinal fractures commonly occur in elderly patients with low bone mineral density. In these cases, percutaneous vertebroplasty or percutaneous kyphoplasty can provide significant pain relief and improve mobility. However, studies have reported both the recurrence of vertebral compression fractures at the index level after vertebroplasty and the development of new vertebral fractures at the adjacent level that occur without any additional trauma. Pedicle screw fixation combined with percutaneous vertebroplasty has been proposed as an effective procedure for addressing osteoporotic thoracolumbar fractures. However, in osteoporotic populations, pedicle screws can loosen, pullout, or migrate. Currently, the efficacy of cortical bone trajectory screw fixation for osteoporotic fractures remains unclear. Thus, we assessed the effects of using cortical bone trajectory instrumentation with vertebroplasty on patient outcomes. Method: We retrospectively reviewed data from 12 consecutively sampled osteoporotic thoracolumbar fracture patients who underwent cortical bone trajectory instrumentation with vertebroplasty. Patients were enrolled beginning in October 2015 and were followed for >24 months. Result: The average age was 74 years, and the average dual-energy x-ray absorptiometry T-score was −3.6. The average visual analog scale pain scores improved from 8 to 2.5 after surgery. The average blood loss was 36.25 mL. All patients regained ambulation and experienced reduced pain post-surgery. No recurrent fractures or instrument failures were recorded during follow-up. Conclusions: Our findings suggest that cortical bone trajectory instrumentation combined with percutaneous vertebroplasty may be a good option for treating osteoporotic thoracolumbar fractures, as it can prevent recurrent vertebral fractures or related kyphosis in sagittal alignment.