Healing of bone fractures highly depends on the biocompatibility, stability in biological conditions, biodegradability, technical functionality, and shelf‐life of biomaterials. Metallic biomaterials offer excellent mechanical properties and biocompatibility. However, metallic bone implants result in stress shielding, release of toxic ions, excessive wear, and corrosion. Polymer materials are being explored for bone implants due to their light‐weight, biocompatibility, biodegradability, and absence of stress shielding. In the new era, additive manufacturing (AM) is being preferred due to its capability of fabricating customer specific implants with minimum material wastage. However, AM based polymer implants lack in mechanical strength and biological properties. Surface modification of polymeric substrates using coatings and incorporation of bioadditives have been regarded as alternatives for improvement of mechanical and biological properties. This review discusses about various coating techniques and gives an overview about coatings and bioadditives that can be used for enhancement of properties. From the review, it is evident that reinforcement of hydroxyapatite to polylactic acid resulted in prevention of crack growth during shape recovery cycles which can be used for self‐fitting implants. Coatings have been successful in enhancing hydrophilicity, mechanical properties, anti‐biofouling, antibacterial and anti‐coagulative properties, adhesion, proliferation, and differentiation of cells on the coated surface. This review also discusses the challenges that need to be overcome for progression in this field.
In engineering applications, there are various types of boilers such as water tube boilers, fire tube boilers, packaged boiler, fluidized bed combustion boiler, pulverized fuel boiler and waste heat boilers. These boilers are used in different industries such as power plants, paper, and chemical. The present paper reports various problems (such as agglomeration, slagging, fouling, caustic embrittlement, fatigue failure and high temperature corrosion) related to boilers and their possible solutions. Some of the controlling parameters for high temperature corrosion has also been studied viz use of inhibitors, varying temperature and pressure, sol-gel coating and thermal spray coating. Thermal spraying has emerged as a main tool for improvement in surface. Problem of corrosion, wear resistance, electrical or thermal insulation can be altered using different coating techniques and materials. Deposition of ash in biomass-fired boilers also causes severe problems of agglomeration. The problem of agglomeration can be solved using kaolin or NH 3 in the bed of boilers. Some important processes such as pulse detonation wave technology, intelligent soot blower, chemical treatment technology can be used to minimize the effects of fouling.
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