## 4 Current Progress and Other Applications  
Taking YSZ, one of the most widely used and mature electrolyte materials, as an example, Table 2 compares UHS and FS with other sintering methods. It presents the density, grain size, and conductivity of YSZ samples obtained by different sintering techniques. Subsequently, Table 3 extends this comparison to GDC material, presenting similar comparative data for GDC samples obtained by the same array of sintering methods. In addition to the above advantages, fast sintering techniques such as FS and UHS can also reduce the loss of volatile elements and limit the interdiffusion of elements in multilayered materials. These aforementioned benefits render UHS and FS highly suitable for the advancement of key SOFC materials with great potential for practical use. It is worth noting that, in addition to FS and UHS, a recently proposed method known as electron-beam radiation-assisted synthesis has also emerged as a new avenue for ceramic synthesis. This method uses a powerful electron beam as a heater to sinter oxide powders, with a sintering duration of just 1 s [133; 134]. Electron beam-assisted synthesis technology is both economical and efficient, and it holds significant potential for development and application in the field of SOFCs. Figure 16: SEM and EDS mapping of the cermet composed of Ni-based superalloy and YSZ (1:4 in volume) sintered by the ultrafast method. (**a**) SEM image of sintered cermet, (**b**) EDS mapping of the sintered cermet, (**c**) EDS mapping of Ni, (**d**) EDS mapping of Zr, (**e**) EDS mapping of Y, (**f**) EDS mapping of O. (Reproduced from [131] with permission from Elsevier). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Sintering Method** & **Material** & \begin{tabular}{c} **Sintering** \\ **Temperature** (°C) \\ \end{tabular} & **Dwelling Time** & **Other Sintering Parameters** & \
\begin{tabular}{c} **Average Grain** \\ **Size (nm)** \\ \end{tabular} &
\begin{tabular}{c} **Density (\%)** \\ **80** \({}^{\circ}\)**C (S/cm)** \\ \end{tabular} & **References** \\ \hline CS & 87 SZ & 1500 & 12 h & / & 12 & 97.5 & 0.051 & [135] \\ SPS & 87 SZ & 1100 & 480 s & Applied pressure: 110 MPa & 021 & 96 & 0.057 & [135] \\ MWS & 87 SZ & 1500 & / & Power: 11.14W & 0.9 & 98 & 0.036 & [136] \\ FS & 87 SZ & 565 (furrace & 600 s & Electric field: 300 V/cm & 0.2 & 96 & 0.056 & [75] \\  & & & Current density: 5.8 & & & & \\ UHS & 37 SZ & 1755 & 60 s & Carbon felt: 80 \(\times\) 30 \(\times\) 5 mm\({}^{3}\) & 0.18 & 99 & / & [127] \\  & 87 SZ & 1439 & 120 s & Current 13 A & 1.9 & 98.6 & / & [128] \\  & & & Carbon felt: 40 \(\times\) 9.5 \(\times\) 4 mm\({}^{3}\) & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Properties of YSZ samples obtained from different sintering techniques. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sintering Method** & **Material** & \begin{tabular}{c} **Sintering** \\ **Temperature** (°C) \\ \end{tabular} & **Dwelling Time** & **Other Sintering Parameters** & \
\begin{tabular}{c} **Average Grain** \\ **Size (nm)** \\ \end{tabular} & **Density (\%)** &
\begin{tabular}{c} **Conductivity at** \\ **80** \({}^{\circ}\)**C (S/cm)** \\ \end{tabular} & **References** \\ \hline CS & 10 GDC & 1500 & 10 h & / & 1.2 & 95 & \(-\)0.008 & [137] \\ SPS & 10 GDC & 980 & 300 s & Applied pressure: 50 MPa & \(-\)0.2 & 98 & \(-\)0.01 & [138] \\ MWS & 10 GDC & 1500 & / & Maximum power: 5.5 MPa & 0.9 & 95 & \(-\)0.05 & [139] \\  & & & Electron: 2.5 GHz & 0.9 & 95 & \(-\)0.05 & [139] \\ FS & 10 GDC & 600 (furrace & 120 s & Electric field: 100 V/cm & 0.2 & 98.9 & 0.013 & [65] \\  & & & Current density: 13.5 m/mm\({}^{2}\) & & & & \\ UHS & 10 GDC & \(>\)1500 & 360 s & Current stepwise to 25 A & / & 95 & / & [102] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Properties of GDC samples obtained from different sintering techniques. UHS and FS are innovative techniques for ceramic sintering that utilize electric current and have gained considerable interest in recent times.