WUT激光熔覆技术
激光熔覆技术是一种通过高能激光束将熔覆材料（粉末、丝材等）与基体表面薄层同时熔化，经快速凝固形成冶金结合涂层的表面改性与修复技术。其核心是利用激光的高能量密度实现材料的精准熔化与结合，相比传统热喷涂、堆焊等技术，在涂层性能、基体保护及精度控制上具有显著优势。
一、技术原理：
激光熔覆的核心是通过高能激光束（功率密度通常为 10⁴-10⁶W/cm²）聚焦于基体表面，使基体表层（数十至数百微米）与预置或同步送入的熔覆材料在极短时间内吸收能量并熔化，形成熔池。随后，激光束移动，熔池在基体自身散热作用下快速凝固，最终在基体表面形成与基体呈冶金结合（原子级结合）的涂层。这一过程的激光能量高度集中，仅作用于特定区域，避免基体整体受热；快速凝固则可细化晶粒，抑制脆性相生成，赋予涂层优异的力学性能。
二、技术特点：
1. 涂层与基体结合强度极高，可靠性突出：激光熔覆形成的是冶金结合（结合强度通常＞300MPa，远高于超音速喷涂的机械结合（50-150MPa）和堆焊的局部结合），涂层与基体不存在物理界面，可承受高载荷、强冲击等极端工况（如航空发动机叶片的高频振动），几乎不会出现剥落或分层。
2. 热影响区（HAZ）极小，基体损伤可忽略：激光能量密度高且作用时间短（通常＜10ms），基体受热区域仅局限于熔池下方的薄层（热影响区厚度通常＜50μm，甚至可控制在 10μm 以内），远低于堆焊（热影响区可达数毫米）和等离子喷涂（数十至数百微米）。因此，基体几乎不会发生变形、开裂或性能退化（如热处理钢的硬度下降、铝合金的过烧），尤其适合精密部件（如模具、汽轮机叶片）的修复与强化。
3.涂层质量优异，成分与性能可控性强：致密度高：激光熔池的剧烈对流可消除气孔、夹杂，涂层致密度接近 100%，远高于热喷涂；成分均匀：通过精确控制熔覆材料的送入速率与激光能量，可实现涂层成分的精准调控（如梯度功能涂层，从基体到表层成分连续变化，避免界面应力）；显微组织优异：快速凝固可细化晶粒（形成超细晶或非晶结构），显著提升涂层的硬度、耐磨性、耐腐蚀性（如 WC 增强镍基合金涂层，硬度可达 60-70HRC，耐磨性比基体提高 5-10 倍。
4.材料利用率高，适用范围广：熔覆材料仅在激光作用区熔化，几乎无飞溅，材料利用率可达 80%-95%（堆焊通常仅 30%-50%）；可适配多种材料组合：基体可为钢、铝、钛、镁等金属，熔覆材料可为合金（Ni 基、Co 基、Fe 基）、陶瓷（Al₂O₃、WC、TiC）、金属间化合物（TiAl）等，甚至可实现异种材料的结合（如铝基体上熔覆不锈钢）。
三、应用领域：
激光熔覆技术可实现从 “强化” 到 “修复” 的全场景覆盖，因优异的性能，广泛应用于高端装备的表面强化与损伤修复，典型场景包括：
1.航空航天：修复发动机涡轮叶片、燃烧室的磨损或裂纹（如镍基高温合金叶片熔覆 Co 基合金，恢复尺寸并提升耐高温性能）；
2.石油化工：对输油管道、泵阀等部件熔覆耐蚀合金（如 NiCrMo），抵抗硫化氢、酸碱腐蚀；
3.电力能源：修复汽轮机转子、叶片的汽蚀、磨损（如 304 不锈钢基体熔覆 WC-Ni 涂层，延长寿命 3-5 倍）；
4.模具制造：对冲压模、压铸模表面熔覆高硬度合金（如 Cr₃C₂增强 Fe 基合金），提升耐磨性，延长模具寿命 2-3 倍；
5.轨道交通：对高铁轮对、轨道辙叉熔覆耐磨涂层（如 Fe-Cr-B-Si 合金），减少磨耗，降低维护成本。
WUT Laser Cladding Technology
Laser cladding technology is a surface modification and repair technique that uses a high-energy laser beam to simultaneously melt cladding materials (powder, wire, etc.) and a thin substrate layer. After rapid solidification, it forms a metallurgically bonded coating. Its core advantage lies in leveraging the laser's high energy density for precise material fusion, offering superior coating performance, substrate protection, and precision control compared to traditional thermal spraying or welding.
I. Technical Principle
The core of laser cladding is to focus a high-energy laser beam (usually with a power density of 10 ⁴ -10 ⁶ W/cm ²) on the surface of the substrate, so that the surface layer of the substrate (tens to hundreds of microns) absorbs energy and melts in a very short time with the pre-set or synchronously fed cladding material, forming a molten pool. Subsequently, the laser beam moves and the molten pool rapidly solidifies under the heat dissipation effect of the substrate itself, ultimately forming a metallurgical bonding (atomic level bonding) coating on the surface of the substrate. The laser energy in this process is highly concentrated and only acts on specific areas to avoid overall heating of the substrate; Rapid solidification can refine the grain size, suppress the formation of brittle phases, and endow the coating with excellent mechanical properties.
II. Technical Advantages
1.The bonding strength between the coating and the substrate is extremely high, with outstanding reliability: Laser cladding forms a metallurgical bond (bonding strength is usually>300MPa, much higher than the mechanical bond of supersonic spraying (50-150MPa) and the local bond of surfacing). There is no physical interface between the coating and the substrate, and it can withstand extreme working conditions such as high load and strong impact (such as high-frequency vibration of aircraft engine blades), with almost no peeling or delamination.
2.The heat affected zone (HAZ) is extremely small, and the damage to the substrate can be ignored: the laser energy density is high and the action time is short (usually<10ms), and the heated area of the substrate is limited to a thin layer below the melt pool (the thickness of the HAZ is usually<50 μ m, and can even be controlled within 10 μ m), which is much lower than that of stack welding (the HAZ can reach several millimeters) and plasma spraying (tens to hundreds of micrometers). Therefore, the matrix will hardly undergo deformation, cracking, or performance degradation (such as a decrease in hardness of heat-treated steel or overburning of aluminum alloys), making it particularly suitable for the repair and strengthening of precision components such as molds and turbine blades.
3.Excellent coating quality, strong controllability of composition and performance: high density: the intense convection of the laser melt pool can eliminate pores and inclusions, and the coating density is close to 100%, far higher than thermal spraying; Uniform composition: By precisely controlling the feeding rate and laser energy of the cladding material, precise control of the coating composition can be achieved (such as gradient functional coatings, where the composition continuously changes from the substrate to the surface layer to avoid interface stress); Excellent microstructure: Rapid solidification can refine grains (forming ultrafine or amorphous structures), significantly improving the hardness, wear resistance, and corrosion resistance of coatings (such as WC reinforced nickel based alloy coatings, with a hardness of 60-70HRC and wear resistance 5-10 times higher than the substrate).
4.High material utilization rate and wide application range: The cladding material only melts in the laser action zone, with almost no spatter, and the material utilization rate can reach 80% -95% (welding usually only 30% -50%); Can adapt to various material combinations: the substrate can be steel, aluminum, titanium, magnesium and other metals, and the cladding material can be alloys (Ni based, Co based, Fe based), ceramics (Al₂O₃、WC、TiC）、 Intermetallic compounds such as TiAl can even achieve the bonding of dissimilar materials (such as stainless steel cladding on an aluminum substrate).
III. Application areas:
Laser cladding technology can achieve full scene coverage from "strengthening" to "repair". Due to its excellent performance, it is widely used for surface strengthening and damage repair of high-end equipment. Typical scenarios include:
1.Aerospace: Repair wear or cracks on engine turbine blades and combustion chambers (such as nickel based high-temperature alloy blades coated with Co based alloy, restoring size and improving high-temperature resistance);
2.Petrochemical industry: Coating corrosion-resistant alloys (such as NiCrMo) on oil pipelines, pumps, valves, and other components to resist hydrogen sulfide and acid-base corrosion;
3.Electric energy: repair cavitation and wear of steam turbine rotors and blades (such as WC-Ni coating on 304 stainless steel substrate, extending service life by 3-5 times);
4.Mold manufacturing: Melt high hardness alloys (such as Cr₃C₂ reinforced Fe based alloys) on the surface of stamping and die-casting molds to improve wear resistance and extend mold life by 2-3 times;
5.Rail transit: Melt wear-resistant coatings (such as Fe-Cr-B-Si alloy) on high-speed rail wheelsets and track crossings to reduce wear and maintenance costs.