Fabrication and microstructure of ZrB_2–ZrC–SiC coatings on C/C composites by reactive melt infiltration using ZrSi_2 alloy

ZrB_2–ZrC–SiC ternary coatings on C/C composites are investigated by reactive melt infiltration of ZrSi_2 alloy into pre-coatings. Two different pre-coating structures, including porous B_4C–C and dense C/B, are designed by slurry dip and chemical vapor deposition(CVD) process respectively. The coating prepared by reactive melt infiltration(RMI) into B_4C–C presents a flat and smooth surface with a three-layer cross-sectional structure, namely interior SiC transition layer, gradient ZrB_2–ZrC–SiC layer, and ZrB_2–ZrC exterior layer. In comparison, the coating prepared by RMI into C/B shows a more granular surface with a different three-layer cross-sectional structure, interior unreacted B–C pre-coating layer, middle SiC layer, and exterior ZrB_2–ZrC–ZrSi_2 layer. The forming mechanisms of the specific microstructures in two coatings are also investigated and discussed in detail.

Repairing skull defects in children with nano-hap/collagen composites: A clinical report of thirteen cases

Objective:To evaluate the clinical results of repairing skull defects with biomimetic bone(nano-hap/collagen composites,NHACs)in children.Methods:Thirteen children with skull defects were treated with NHACs in our hospital.The NHACs molded with the help of a 3D printer were used in the operations.Results:All 13 operations were successful,and patients recovered without infection.Only one patient suffered from subcutaneous hydrops post-operation.The implanted NHACs remained fixed well after 1 year,and their CT HU values raised gradually.Skull shapes of children developed normally.Recovery of neurological and cognitive function was significant.Conclusions:NHAC,chosen to repair skull defects in children,can coexist with normal skull and reduce the negative effects on growth and development.NHAC could be a good choice for children with skull defects.

Investigation of operative skills and cranioplasty complications using biomimetic bone(nano-hap/collagen composites)

The aim of the current study was to investigate the operation skills and complications associated with skull defect repair using biomimetic bone(nano-hap/collagen composites). Clinical data from 45 patients with skull defects who underwent cranioplasty with biomimetic bone from January 2014 to January 2017 were retrospectively analyzed.All patients participated in follow-up visits from 8 months to 3 years postoperatively. Cranioplasties were successful in all 45 patients,but 17 patients(20 cases) presented various complications, including subcutaneous hydrops(14 cases), biomimetic bone fixation loosening(4 cases), wound indolence(1 case), and biomimetic bone fragmentation(1 case). Cranioplasty complications in surgeries using biomimetic bone are more common in children than in adults.Understanding the physicochemical properties of biomimetic bone and the normal developmental process in children, as well as mastering the appropriate surgical skills and implementing the effective preventive measures are all ways to reduce and control the incidence of complications associated with biomimetic bone cranioplasty.