Formation of Amorphous Fe-Cr-Mo-8P-2C Coatings by HVOF Process

Fe-10%Cr-8%P-2%C(10Cr), Fe-20%Cr-8%P-2%C(20Cr) and Fe-10%Cr-10%Mo-8%P-2%C(10Mo) alloy powders (mass percent) were sprayed by the HVOF process under different conditions. The as-sprayed coatings of 10Mo alloy were composed of only an amorphous phase under all the spray conditions, while the as-sprayed coatings of the 10Cr and 20Cr alloys consisted of an amorphous phase with a small amount of crystalline material. The volume fraction of the crystalline material increased slightly with the rise of the flame temperature. The hardness of the as-sprayed coatings of the 10Cr and 20Cr alloys were 600 to 700 DPN, respectively, while the 10Mo coating composed of an amorphous phase revealed 560 DPN. The corrosion resistance of the as-sprayed coating of the 10Mo alloy was the best among three amorphous coatings and also superior to the nickel base self-fluxing alloy and SUS316L stainless steel coatings in 1N H2SO4 and 1N HCl solutions

Formation of Amorphous Fe-Cr-Mo-8P-2C Coatings by HVOF Process

Fe-10%Cr-8%P-2%C(10Cr), Fe-20%Cr-8%P-2%C(20Cr) and Fe-10%Cr-10%Mo-8%P-2%C(10Mo) alloy powders (mass percent) were sprayed by the HVOF process under different conditions. The as-sprayed coatings of 10Mo alloy were composed of only an amorphous phase under all the spray conditions, while the as-sprayed coatings of the 10Cr and 20Cr alloys consisted of an amorphous phase with a small amount of crystalline material. The volume fraction of the crystalline material increased slightly with the rise of the flame temperature. The hardness of the as-sprayed coatings of the 10Cr and 20Cr alloys were 600 to 700 DPN, respectively, while the 10Mo coating composed of an amorphous phase revealed 560 DPN. The corrosion resistance of the as-sprayed coating of the 10Mo alloy was the best among three amorphous coatings and also superior to the nickel base self-fluxing alloy and SUS316L stainless steel coatings in 1N H2SO4 and 1N HCl solutions

Properties of Cr3C2-NiCr Cermet Coating Sprayed by High Power Plasma and HVOF Processes

The structure, hardness and shear adhesion strength have beeninvestigated in Cr3C2-NiCr cermet coatings sprayed onto a mild steelsubstrate by 200 kW high power plasma spraying (HPS) and high velocityoxy-fuel (HVOF) processes. Amorphous and supersaturated nickel phasesform in both as-sprayed coatings. The hardness of the HVOF coating ishigher than that of the HPS coating because the HVOF coating containsmore non-melted Cr3C2 carbide particles. On heat-treating at 873 K, theamorphous phase decomposes and the supersaturated nickel phaseprecipitates Cr3C2 carbides so that the hardness increases in the HPScoating. The hardness measured with a large load exhibits lower valuescompared with that measured with a small load because of cracksgenerated from the indentation. The ratio of the hardnesses measuredwith different loads can be regarded as an index indicating the coatingductility. The ductility of the HVOF coating is higher than that of theHPS coating. Adhesion strength of the HVOF coating was high comparedwith the HPS coating. The adhesion of the coatings is enhanced byheat-treating at 1073K and that of the HVOF coating was over 350 MPa

Meniscus Repair With Anterior Cord Release for Peripheral Tear Type of Discoid Lateral Meniscus

With improvement in arthroscopic techniques, partial meniscectomy with repair for symptomatic discoid lateral meniscus (DLM) has been the preferred treatment to restore meniscal function. It was reported that DLM exhibited deformation and extrusion shortly after saucerization with repair. Therefore it is desirable to minimize removal of the DLM. The anterior zone of the DLM is often tighter than that of the normal meniscus and anatomic variant. It is considered that the anterior and anterocentral dislocation types in the majority of symptomatic DLM can be related to both peripheral instability and anterior tightness. We present a technique that, first, the inside-out repair technique is applied from the posterior to middle segment of the DLM; next, the tension of the anterior zone during knee flexion–extension is confirmed to determine the released amount of that part; and, finally, all sutures are tied to reproduce the normal meniscus movement. Meniscus repair with anterior cord release without any meniscectomy could resolve peripheral instability of DLM and prevent degeneration of the articular cartilage

IGF-1 Gene Transfer to Human Synovial MSCs Promotes Their Chondrogenic Differentiation Potential without Induction of the Hypertrophic Phenotype

Mesenchymal stem cell- (MSC-) based therapy is a promising treatment for cartilage. However, repair tissue in general fails to regenerate an original hyaline-like tissue. In this study, we focused on increasing the expression levels for insulin-like growth factor-1 (IGF-1) to improve repair tissue quality. The IGF-1 gene was introduced into human synovial MSCs with a lentiviral vector and examined the levels of gene expression and morphological status of MSCs under chondrogenic differentiation condition using pellet cultures. The size of the pellets derived from IGF-1-MSCs were significantly larger than those of the control group. The abundance of glycosaminoglycan (GAG) was also significantly higher in the IGF-1-MSC group. The histology of the IGF-1-induced pellets demonstrated similarities to hyaline cartilage without exhibiting features of a hypertrophic chondrocyte phenotype. Expression levels for the Col2A1 gene and protein were significantly higher in the IGF-1 pellets than in the control pellets, but expression levels for Col10, MMP-13, ALP, and Osterix were not higher. Thus, IGF-1 gene transfer to human synovial MSCs led to an improved chondrogenic differentiation capacity without the detectable induction of a hypertrophic or osteogenic phenotype