电解沉积铬板是目前起落架部件界面表面的标准表面处理方法，要求具有良好的耐磨性和防腐性。镀铬部件通常存在疲劳性能轻微下降、有害的泥浆开裂表面模式、易划伤、磨损和密封泄漏等问题。此外，最近环境合规标准的变化进一步限制了电解沉积铬的使用。一些商业应用已经在当前和未来的产品上取消了镀铬。 因此，多年来，人们一直在寻找电解沉积铬板的替代品。高速含氧燃料（HVOF）热喷涂涂层已经发展到可以替代硬铬板在高强度低合金钢上用于起落架外表面的程度。HVOF涂层的一些特性，如疲劳性和耐磨性优于硬铬板。然而，性能特征，例如在非常高的应变下的附着力，显然是不同的。 本文件旨在概述和描述HVOF碳化钨涂层的设计和使用指南，以确保起落架设备的适当质量和性能。本文件不作为HVOF涂层涂覆的详细工艺规范。此外，本文件中的建议不一定适用于某些专有喷涂系统（即D-GunsT）。本文件中的信息仅适用于高强度钢合金的HVOF碳化钨基涂层，不一定适用于其他基材。

Electrolytically deposited chrome plate is the current standard surface treatment for landing gear component interface surfaces that require good wear resistance and corrosion protection. Chrome plated components are typically plagued by a slight debit in fatigue performance, detrimental mud cracking surface pattern, susceptibility to scoring, wear, and seal leakage. In addition, recent changes in environmental compliance standards place further restrictions on the use of electrolytically deposited chromium. Some commercial applications have already eliminated the use of chrome plate on current and future products. As a result, a substitute for electrolytically deposited chrome plate has been sought for several years.High Velocity Oxygenated Fuel (HVOF) thermal spray coatings have been developed to the point where they are being implemented as an alternative to hard chrome plate on high strength low alloy steels for external surfaces on landing gear applications. Some of the characteristics of HVOF coatings, such as fatigue and wear resistance are superior to hard chrome plate. Yet, performance characteristics, such as adhesion under very high strains, are clearly different. This document is intended to outline and describe the design and usage guidelines for HVOF tungsten carbide coatings to assure adequate quality and performance of the landing gear equipment. This document is not intended to act as a detailed process specification for applying HVOF coatings. Also, the recommendations in this document do not necessarily apply to certain proprietary spraying systems (i.e., D-Gun\sT).The information in this document pertains to HVOF tungsten carbide based coatings applied to high strength steel alloys only, and is not necessarily applicable to other substrates.