Editing Chrome plating (section)

==Types==
===Decorative===
[[File:Portfolio MET DP291203.jpg|thumb|[[Art Deco]] portfolio with chrome-plated cover, ca 1925]]

''{{visible anchor|Decorative chrome}}'' is designed to be aesthetically pleasing and durable. Thicknesses range from {{convert|2|to|20|μin|μm|abbr=on|sigfig=1}}, however, they are usually between {{convert|5|and|10|μin|μm|abbr=on}}. The chromium plating is usually applied over bright [[Nickel electroplating|nickel plating]]. Typical base materials include [[steel]], [[aluminium]], [[plastic]], [[copper]] alloys, and zinc alloys.<ref name="newmoa"/> Decorative chrome plating is also very corrosion resistant and is often used on car parts, tools and kitchen utensils.{{Citation needed|date=April 2021}}

=== Thin Dense Chrome ===
''Thin dense chrome (TDC)'' differs from decorative chrome.<ref>{{Cite web |last=Jordan |date=2022-12-21 |title=Understanding the Thin Dense Chrome Plating Process |url=https://armoloy.com/understanding-the-thin-dense-chrome-plating-process/ |access-date=2024-09-24 |website=The Armoloy Corporation |language=en-US}}</ref> While decorative chrome is applied primarily for aesthetic purposes with thin layers that provide a shiny finish, TDC, such as [[The Armoloy Corporation|Armoloy]], focuses on enhancing surface performance. It delivers wear resistance, corrosion protection, and hardness without adding significant thickness. TDC also avoids the microcracking associated with decorative chrome, making it ideal for industrial applications where durability and friction reduction are necessary. Thin dense chrome is commonly used in precision tools, aerospace, medical, and food processing equipment.

===Hard===
[[Image:Hard chrome finish.png|thumb|upright|Hard chrome plating]]
''{{visible anchor|Hard chrome}}'', also known as ''{{visible anchor|industrial chrome}}'' or ''{{visible anchor|engineered chrome}}'', is used to reduce friction, improve durability through abrasion tolerance and wear resistance in general, minimize [[galling]] or seizing of parts, expand chemical inertness to include a broader set of conditions (such as oxidation resistance), and bulking material for worn parts to restore their original dimensions.<ref>{{cite web|url=http://www.everyspec.com/FED_SPECS/Q/download.php?spec=QQ-C-320B.008739.PDF|title=QQ-C-320B|website=everyspec.com|access-date=3 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170816193017/http://everyspec.com/FED_SPECS/Q/download.php?spec=QQ-C-320B.008739.PDF|archive-date=16 August 2017}}</ref> It is very hard, measuring between 65 and 69 [[Rockwell scale|HRC]] (also based on the base metal's hardness). Hard chrome tends to be thicker than  decorative chrome, with standard thicknesses in non-salvage applications ranging from 20 to 40 μm,<ref>{{cite web|url=http://www.uschrome.com/design-recommendations-for-hard-chrome-plating/|title=Design Recommendations For Hard Chrome Plating|publisher=U.S. CHrome Corporation|archive-url=https://web.archive.org/web/20170816193518/http://www.uschrome.com/design-recommendations-for-hard-chrome-plating/|archive-date=2017-08-16|url-status=live|access-date=16 August 2017}}</ref> but it can be an order of magnitude thicker for extreme wear resistance requirements, in such cases 100 μm or thicker provides optimal results. Unfortunately, such thicknesses emphasize the limitations of the process, which are overcome by plating extra thickness then grinding down and lapping to meet requirements, or to improve the overall aesthetics of the chromed piece.<ref name="newmoa"/> Increasing plating thickness amplifies surface defects and roughness in proportional severity, because hard chrome does not have a leveling effect.<ref>{{Citation | last1 = Degarmo | first1 = E. Paul | last2 = Black | first2 = J T. | last3 = Kohser | first3 = Ronald A. | title = Materials and Processes in Manufacturing | publisher = Wiley | page = 793 | year = 2003 | edition = 9th | isbn = 0-471-65653-4}}.</ref> Pieces that are not ideally shaped in reference to electric field geometries (nearly every piece sent in for plating, except spheres and egg shaped objects) require even thicker plating to compensate for non-uniform deposition, and much of it is wasted when grinding the piece back to desired dimensions.{{Citation needed|date=April 2021}}

Modern engineered coatings do not suffer such drawbacks, which often price hard chrome out due to labor costs alone. Hard chrome replacement technologies outperform hard chrome in wear resistance, corrosion resistance, and cost. Hardness up to 80 HRC is not extraordinary for such materials. Modern engineered coatings applied using [[Thermal spray|spray deposition]] can form layers of uniform thickness that often require no further polishing or machining. These coatings are often composites of [[polymers]], metals, and ceramic powders or fibers as proprietary formulas protected by patents or as trade secrets, and thus are usually known by brand names.<ref>{{cite journal|last1=Vernhes|first1=Luc|title=Alternatives for hard chromium plating: Nanostructured coatings for severe-service valves|journal=Materials Chemistry and Physics|date=2013|volume=140|issue=2–3|pages=522–528|doi=10.1016/j.matchemphys.2013.03.065}}</ref>

Hard chromium plating is subject to different types of quality requirements depending on the application; for instance, the plating on hydraulic [[piston rod]]s are tested for corrosion resistance with a [[salt spray test]].{{Citation needed|date=April 2021}}