Karakterisasi penguat carbon nanotube terhadap penigkatan ketahanan aus dan self-lubrication cylinder liner dan cincin torak berbasis pelapisan CNT-Al2O3 nanokomposit dengan metode penyemprotan dingin = Characterization of carbon nanotube strengthening to improving wear resistance and self lubrication coating cylinder liner and piston ring with CNT-Al2O3 coating by cold spraying