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The mechanical response to indentation (including nano- and microindentation) has been investigated in Cu/Au and Cu/Cr multilayers with respective layer thickness ratios of 1:1 and 2:1, and individual layer thickness ranging from nanometer to submicrometer scale. It was found that the Cu/Cr multilayer has higher strength than the Cu/Au multilayer, although both multilayers have close Hall–Petch slope. Examination of indentation-induced deformation behavior shows that the Cu/Cr multilayer exhibits higher resistance to plastic deformation instability than the Cu/Au multilayer. Theoretical analysis indicates that the significant difference in mechanical response originates from the constituent layer configuration and interface structures, which impose distinguishing confining effect on dislocation activity.

Fly ash compounds, such as alkali salts, in the raw biomass fuel gas can contaminate and deposit on traditional granular Ni-based catalysts, which resulted in catalyst deactivation and pressure increase of the downstream reformer. The impact of alkali salt exposure (KCl, K 2 SO 4 , K 2 CO 3 , by evaporation at about 7.8 mg/L for 6 h) on dry CH 4 /CO 2 reforming of model biomass fuel gas (H 2 /CO/C 2 H 4 /CH 4 /CO 2 / N 2) 15.8/12.1/2.51/ 15.0/22.1/32.6 vol %) over Ni-MgO/γ-Al 2 O 3 /cordierite monolithic catalyst (MC) was investigated and studied. The results showed that CH 4 and CO 2 conversions and CO and H 2 yields increased at 700-850°C for undeposited and deposited MC. Compared with undeposited MC, the deposited catalysts show lower CH 4 conversion but higher CO 2 conversion and CO yield at 750-830°C. The stability tests also show that CH 4 conversion and H 2 content in the tail gas decreased dramatically from 87.2% to 32.0% and from 35.1% to 26.7%, respectively, after 17 h time on stream (TOS) for the deposited MC, while CH 4 conversion kept steady of above 90% after 60 h TOS for undeposited MC at 750°C. Characterization by N 2-physisorption, XRD, ICP-AES, SEM-EDS, and XPS of MC indicate that alkali salt aerosol covering the catalyst surface or blocking mesopore channels was the main reason for the decreased reforming performance and MC deactivation, which occurred mainly at the top part of monolithic catalyst (K) 1.39 wt % by EDS), vicinal to the alkali source. The reforming of real biomass fuel gas (H 2 /CO/C 2 H 4 /CH 4 /CO 2 /N 2) 10.2/16.8/0.5/6.4/15.2/51.0 vol %) from air gasification of pine sawdust in the pilot plant (200-250 kg/h) by the reformer packed with MCP, larger in size than MC, exhibits pressure drop of less than 700 Pa, CH 4 conversion of about 84%, and tar content from 4.8-5.3 g/m 3 to 0.12-0.14 g/m 3 during 60 h TOS at 600°C. The porosity structure of MCP catalytic bed and relatively low alkali (K, Na) 0.03-0.07 wt %) deposition by fly ash from real biomass fuel gas were the main reasons for the excellent reformer performance.