The different soot concentration in the flames, and to provide enough material for the nanoindentation evaluation.Table 1. Investigated flame reactor parameters.C/O Ratio Equivalent Ratio Cold gas velocity, cm/s Sampling position, mm Insertions quantity Sample #1 0.67 two.01 9.8 14 100 Sample #2 0.85 2.55 ten 14The AFM instrument utilised in this study was a Scanning Probe Microscope NTEGRA Prima from NTMDT operated at space temperature and 35 relative humidity. Etalon HA_HR_DCP diamondcoated probes were utilized, characterized by a 93 m lengthy dia mondcoated cantilever using a nominal spring force continuous Kc = 85 N/m and a nominal resonant frequency of 580 kHz. Polyethylene naphthalate films (PEN, thickness 0.15 mm, Sigma Aldrich) and highly oriented pyrolytic graphite substrates (HOPG, thickness 2 mm, Sigma Aldrich) were used as reference components. three. Experimental Strategy The AFM was operated in force spectroscopy mode to carry out the nanoindentation measurements. In AFM force measurements, the sample is mounted on a holder attached for the piezoelectric element on the instrument. By applying a voltage for the piezoelectric translator, the sample is moved up and down, and the resulting cantilever deflection is measured by the optical lever method as an electrical signal named DFL and recorded as a function in the piezo displacement [35]. The cantilever deflection, c, is usually then obtained dividing the DFL signal by the photodetector sensitivity, that is derived from the slope of the curve inside the difficult repulsive contact area obtained utilizing cleaved muscovite mica as a tough material [36]. Knowing the cantilever spring constant Kc, the interaction force F acting involving the probe as well as the sample can be just obtained from Hooke’s law as: (1)Taking into consideration that the deflection of the cantilever is generally very smaller, it might be con sidered as an ideal spring. The cantilever spring constant was calculated from the geomet rical beam theory by measuring the resonant frequency and neglecting the diamond coat ing [37,38]. For the strategies utilized in this study, Kc was measured to become equal to 95 5 N/m. The force istance curves are the supply of facts associated to the mechanical qualities of your sample [31,39]. A typical interactive force istance curve measured on a PEN film is reported in Figure 1. The curve is divided into an method plus a retrac tion aspect. Initially, the Pirepemat supplier distance involving tip and surface is significant sufficient to possess no meas urable interaction, the cantilever is not deflected and only the physical separation adjustments because the probe is moved (point A in Figure 1). Because the sample approaches the tip, an instabil ity referred to as “Jumptocontact” occurs and also the cantilever undergoes a fast deflection when the force gradient exceeds the spring continuous (point B in Figure 1). The straight line right after this point is referred to as the contact line. If the cantilever N-Nitrosomorpholine References stiffness exceeds the sample stiffness, because the translator moves additional the tip acts as an indenter and causes a defor mation (point C in Figure 1). Therefore, information about the mechanical properties of theAppl. Sci. 2021, 11,4 ofsample can be deduced. Subsequently, the sample surface is retracted from the probe (point D in Figure 1), the adhesive forces hold the probe towards the sample until the spring continual overcomes the force gradient, and the “Pulloff” instability occurs (point E in Figure 1). The adhesive fo.
