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Xray free-electron lasers (XFELs) enable experiments that would have been impractical or impossible at conventional X-ray laser facilities. Indeed, more XFEL facilities are being built and planned, with their aim to deliver larger pulse energies and higher peak brilliance. While seeking to increase the pulse power, it is quintessential to consider the maximum pulse fluence that a grazing-incidence FEL mirror can withstand. To address this issue, several studies were conducted on grazing-incidence damage by soft X-ray FEL pulses at the European XFEL facility. Boron carbide (B4C) coatings on polished silicon substrate were investigated using 1 keV photon energy, similar to the X-ray mirrors currently installed at the soft X-ray beamlines (SASE3). The purpose of this study is to compare the damage threshold of B4C and Si to determine the advantages, tolerance and limits of using B4C coatings.

Xray free‐electron lasers (XFELs) enable experiments that would have been impractical or impossible at conventional X‐ray laser facilities. Indeed, more XFEL facilities are being built and planned, with their aim to deliver larger pulse energies and higher peak brilliance. While seeking to increase the pulse power, it is quintessential to consider the maximum pulse fluence that a grazing‐incidence FEL mirror can withstand. To address this issue, several studies were conducted on grazing‐incidence damage by soft X‐ray FEL pulses at the European XFEL facility. Boron carbide (B4C) coatings on polished silicon substrate were investigated using 1 keV photon energy, similar to the X‐ray mirrors currently installed at the soft X‐ray beamlines (SASE3). The purpose of this study is to compare the damage threshold of B4C and Si to determine the advantages, tolerance and limits of using B4C coatings. [ABSTRACT FROM AUTHOR]

Boron carbide (B 4 C), silicon carbide (SiC) and silicon nitride (Si 3 N 4) can achieve low coefficient of friction (Cof) under high relative humidity condition. Therefore, B 4 C/SiC and B 4 C/Si 3 N 4 tribo-pairs may exhibit outstanding tribological behaviors, while the tribological investigation is poor. In present investigation, we performed the friction tests of the B 4 C/SiC and B 4 C/Si 3 N 4 tribo-pairs under various relative humidity conditions, and revealed that the B 4 C/SiC tribo-pair is a promising candidate for high relative humidity engineering applications. Surprisingly, the B 4 C/SiC tribo-pair exhibited much better tribological behaviors than the B 4 C/Si 3 N 4 tribo-pair with the same test condition and tribochemical products. This is mainly attributed to less wear debris on the SiC ball and the formation of a stable tribochemical film containing boric acid and silica gel. [ABSTRACT FROM AUTHOR]

Diamond/WC-Fe-Ni composite is a potential composition for impregnated diamond drill bits. It is necessary to avoid the graphitization of the diamond from Fe and Ni under the powder metallurgy process. Boron carbide (B 4 C) was coated on diamond, and diamond/WC-Fe-Ni composites were consolidated by hot pressing at different temperatures. The influences of sintering temperature and interfacial structure on bending strength and wear behavior were investigated. The bending strength for diamond/WC-Fe-Ni composite was dependent on matrix densification and interfacial graphitization. Un-coated diamond was eroded by Fe-Ni matrix and partially converted to graphite during the sintering process at all sintering temperatures. In opposite, B 4 C coating was beneficial to matrix densification at a lower sintering temperature, and delayed the appearance of graphitization to around 1300 °C. Therefore, the diamond/WC-Fe-Ni composites with B 4 C coating exhibited larger bending strength and better wear behavior at a relative low sintering temperature. • B 4 C coating is benefit to matrix densification, and delay the diamond graphitization. • B 4 C coating contributes to enhancement bending strength for diamond/WC-Fe-Ni composite (up to 644 MPa). • B 4 C coating contributes to improvement in abrasive ratio (up to 2417), increased by 6 times. [ABSTRACT FROM AUTHOR]