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Laser cladding is a process whereby a new layer of material is deposited on a substrate by laser fusion of blown powders or pre-placed powder coatings. Multiple layers can be deposited to form shapes with complex geometry. This manufacturing process has been used for material surface property modification and for the repair and manufacture of three-dimensional components. Laser cladding has attracted extensive research over the past 30 years. Over 2000 research papers have been published in journals and international conferences. Research in laser cladding covers many scientific issues, including processing techniques, physical and chemical properties of deposited materials and clad—substrate interfaces, microstructure and phases, rapid solidification phenomena, modelling and simulation, and systems engineering and applications. This article, focusing on the rapid heating/cooling processes and material response, summarizes the state of the art on two fundamental scientific aspects: rapid solidification and the material characteristics. The article includes a review of the microstructural refinement, extended solid solution, metastable phases, amorphous structure, and directional solidification. In addition, the article discusses the progress and state of the art in laser cladding of commercial alloy powders, carbides and intermetallics, in-situ synthesized particulate reinforced metal matrix composite coatings, compositional gradient materials, and alloy development. Laser cladding is capable of producing materials with designed macro/microstructures and properties.

Subchondral bone has been identified as an attractive target for KOA. To determine whether a minimally invasive micro-scaffolds could be used to induce regeneration of knee subchondral bone lesions, and to examine the protective effect of subchondral bone regeneration on upper cartilage, a ready-to-use injectable treatment with nanohydroxyapatite-chitosan-gelatin micro-scaffolds (HaCGMs) is proposed. Human-infrapatellar-fat-pad-derived adipose stem cells (IPFP-ASCs) were used as a cellular model to examine the osteo-inductivity and biocompatibility of HaCGMs, which were feasibly obtained with potency for multi-potential differentiations. Furthermore, a subchondral bone lesion model was developed to mimic the necrotic region removing performed by surgeons before sequestrectomy. HaCGMs were injected into the model to induce regeneration of subchondral bone. HaCGMs exhibited desirable swelling ratios, porosity, stiffness, and bioactivity and allowed cellular infiltration. Eight weeks after treatment, assessment via X-ray imaging, micro-CT imaging, and histological analysis revealed that rabbits treated with HaCGMs had better subchondral bone regeneration than those not treated. Interestingly, rabbits in the HaCGM treatment group also exhibited improved reservation of upper cartilage compared to those in other groups, as shown by safranin O-fast green staining. Present study provides an in-depth demonstration of injectable HaCGM-based regenerative therapy, which may provide an attractive alternative strategy for treating KOA.

In this work, injection moulding and pressureless sintering in hydrogen were applied to manufacture translucent alumina ceramics. Excellent rheological properties of the feedstocks for injection moulding were obtained through a method of powder pretreatment with stearic acid induced by ball milling. Optimum solid loading was confirmed in terms of rheological data and porous properties. The average grain size of the sintered body is 30-50 mm, with no significant pores and abnormal grain growth observed. The real inline transmission is higher and more stable than those via other forming technologies and pressureless sintering reported in previous literatures. As a result, translucent alumina components with small size and high precision were fabricated in such a stable, efficient and low cost route.

We have evaluated the effect of bending strain on the critical current of Bi-2223/Ag tapes with different structures. The measured results were analysed using a symmetric pure bending model. The irreversible degradation indicates that the Ic reduction is caused mainly by crack formation and propagation in the brittle Bi-2223 ceramic core. Experimented results have shown that the number of filaments, as well as the structure of the tapes, could have strong effects on the measured apparent critical values of the tapes. Multifilamentary tapes showed better performance compared with single core tapes. The bending strain tolerance of the tape could be improved by adding a metal strip on the upper side of the tape.