The Research On The In-situ Synthesis Of TiB₂Reinforced Iron-based Composite Coating By SMAW

The metal matrix composites （MMCs）, integrated the metal matrix andreinforcement’s advantages, have been widely used in the aeronautical andastronautical, military, automobile fields. As a typical boride ceramic, TiB₂ceramichas been widely used as the reinforcement in the metal matrix composites （MMCs）because of its high melting point, good chemical stability, high hardness, highmodulus of elasticity, good compatibility and good resistance to abrasion. However,there are a number of shortages in the past researches, such as uneven distribution ofreinforcement, poor repeatability of preparation method, bad shape of coating, highercost due to complex manufacturing processes and unavailable thicker coatings, whichhave greatly restricted the application of MMCs.Different blending ratios of the mixture of ferrotitanium powder （Fe-Ti） andboron carbide powder （B₄C） were used as electrode covering in this paper.TiB₂-reinforced iron-based composites were produced by shielded metal arc welding（SMAW） process. According to the research, the MMCs have excellent properties, sothe process can be used to prepare TiB₂-contained MMCs. The synthesized TiCreinforcement in the coatings depends on the ratio of Ti and B in the covering,according the thermodynamic analysis. As the increase of gravity coefficient ofcoating, the hardness of coating was significant improved due to the proportion ofTiB₂and Fe₂B increased in the MMCs. A thickness of6mm coating can be preparedby SMAW process, which has the advantages of stable structure, good repeatability,even distribution of reinforcement, low price and so on. This preparation process has avery good application prospect.Influences of the high carbon Ferro-chrome （Fe-Cr） on the coating had beeninvestigated in this paper in order to improve the corrosion resistance of the coating.With the addition amounts of Fe-Cr in the electrodes increasing, the TiB₂reinforcements are replaced progressively by TiC reinforcements in the coating andpractically disappear at last. The coating added Fe-Cr possesses better corrosionresistance behavior and higher hardness than the coating without addition.