38baosteel technical research, vol.5, no. i, mar. 2011was very low with many defects. this was resultedsubstrate preheating temperatures were 800 c andfrom the hard oxide flm, which could make it diffcult850c, noxide films occurred in the interfacefor the impacted particles to deposit and the cracksbetween the coating and the substrate. so this is a veryappeared in the edge of the oxide film. when theinteresting phenomenon to be further discussed.coatingoxide filmsubstrateoxide flm20 pm20 pum20四(a) 500c(b)550"c(c) 600cinterface20 m20umi20 μm(d) 650"c(e) 800c(i) 850cc oating20m(g) 900cfig7 interface morphology at different substrate temperaturesfig. 8 shows the particles deposition process when ansuddenly broken into pieces and fallen off theoxide film exists. in the first stage，the particles with asubstrate.i finally , the particles successfully depositedhigh velocity vertically impacted onto the oxide filmon the cleaned and hot substrate and formed a densityand then some cracks occurred in the oxide film. icoating. the experimental results showed that thethe secondary stage , the following particles continu-oxide film thickness was an important factor in theously impacted onto the oxide film，the oxide film was particle deposition process. if the oxide film is thin,.↑rebound↑ rebound↑ reboundimpactcrack(arebound rebound中国煤化工_myhcnmhgfig.8 schematic of the particle deposition characteristics onto a substrate with an oxide film.40baosteel technical research, vol.5, no. 1, mar. 20116029.[13] zahirish, fraser d, gulizia s, et al. efect of. [4]borchers c, gairtner f, stoltenhoff t, et al. micro-processing conditions on porosity formation in cold gastructural andmacroscproperties of cold sprayeddynamic spraying of copper 「j 1，journal of thermalcopper coatings [j]. jourmal of applied physics , 2003,93( 12) :10064-10070.[14] van steenkiste t h,and teets r e.[5] licj,li w y and wang y y. formation of metaaluminum coatings via kinetie spray with relatively largestable phases in cold-sprayed soft metallic deposit [ j].powder particles [j]. surface coating and technology ,surface coating and technology ,2005 , 198 :469-473.2002,154 :237-252.[6 ] dykhuizen r c ,smith m f,gilmore d l,er al. impactof high velocity cold spray particles [ j]. journal ofthermal spray technology , 1999 ,8(4) :559-564.[ 7 ] borchers c, girtner f, stoltenhoff t, et al. micro-structural bonding features of cold sprayed face centeredcubic metals [ j]. journal of applied physics ,2004 , 96(8) :4288- 4292.[8] schmidt t, assadi h, girtner f,et al. from particleacceleration to impact and bonding in cold spraying [ j] .journal of thermal spray technology ,2009，18 :794-808.raletz f, vardelle m and e'o g. critical particlemeng xianmingzhang junbaoliang yonglicoating and technology ,2006 ,201 :1942-1947.[10] gilmore d l, dykhuizen r c,neiser r a,er al. particlevelocity and deposition effciency in the cold sprayprocess [ j]. journal of thermal spray technology,1999 ,8(4) :576-582.[11] assadi h, girtner f, stoltenhoff t, et al. bondingmechanism in cold gas spraying [ j ]. acta materialia,2003 ,51(15) :43794394.[12] leejh, shin s, kim h j, et al. effect of gastemperature on critical velocity and deposition charac-zhao jie .teristics in kinetic spraying[ j]. applied surfacescience ,2007 ,253:3512-3520.中国煤化工mhcnmh g.
