October 2012 Archives

#136 Mechanical Properties of Functional Plating

By システム管理者 on October 26, 2012 12:00 AM | No Comments | No TrackBacks

The following are the required properties of the functional platings.

Required characteristics	Plating type	Application example
High hardness	Industrial chrome, Electroless nickel plating, Composite nickel plating, Rhodium plating	Cylinders, Rolls, Various molds, Gauges, Bearings, etc.
Lubricity	Industrial chrome, Silver, Indium, Tin, Lead, Composite plating	Cylinders, Piston rings, Bearings, Shafts, etc.
Dimensional accuracy	Electroless nickel	Precision machine components, Precision molds, Shafts, Bearings, etc.
Buildup	Industrial chrome, Copper, Nickel	Rolls, Bearings, Cylinders, Crank shafts, Molds, etc.
Demolding characteristics	Industrial chrome, Composite nickel	Various molds
Low friction coefficient	Industrial chrome, Composite nickel	Papermaking rolls, Thread feed rolls, Guides

(1) Hardnes

Hardness of plating layers are represented in Micro Vickers Hv and Knoop Hk hardness values. The industrial chrome plating can attain Hv800~1000, and heat treated electroless nickel plating can attain Hv1000. Also, composite plating where minute particles of alumina and silicon carbide are dispersed in nickel plating can attain Hv600. These can achieve Hv1300~1400 by heat treating. Nickel-tungsten alloy plating is also spotlighted as a high hardness plating.

(2) Lubricity

The term Lubricity includes low friction coefficient, lubricant retention characteristics, and conformability. For bearings, lead-tin alloy, lead-indium alloy, lead-tin-antimony alloy, and silver give the conformability. When wear resistance is needed, lubrication impregnated composite plating or porous chrome plating are used. For the lubricity and wear resistance purposes, composite platings where minute particles of graphite fluoride or molybdenum disulfide are dispersed.

(3) Dimensional accuracy

There are issues in uneven plating current with electroplating, and is difficult to evenly deposit the coatings everywhere on the objects. But with electroless platings that do not use electricity, it is possible to obtain even coating layers easily. There are nickel-phosphate plating and nickel-boron alloy plating.

(4) Buildup characteristics

This is a type of plating used for dimensional corrections and repairs, as well as good wear resistance, corrosion resistance, hardness, machinability are required at the same time. The plating types able to achieve high harness and thick plating layers are used.

(5) Demolding characteristics

This is required for mold applications, and the industrial chrome plating is used. Instead of the chrome plating, graphite fluoride dispersed nickel plating is also used, contributing in prolonging mold lives.

(6) Low friction coefficient

This is also termed "sliding properties", and is required for papermaking roller and guide applications. Teflon impregnated industrial chrome plating and molybdenum disulfide codeposited nickel composite plating are attracting the attention.

#135 Industrial Chrome Plating

By システム管理者 on October 19, 2012 12:00 AM | No Comments | No TrackBacks

The industrial chrome plating, also customarily called hard chrome plating, has been in wide usage in many areas in 10 ~ 100μm thickness due to its chrome coating hardness, lubrication retention ability, and wear resistant properties.

The industrial chrome plating coating properties are as follows.

(1) High hardness

Hardest among the standard electroplating (Macro Vickers hardness approx. 1000). Much harder than heat treated or nitrided steels.

(2) Wear resistance

The most importantly expected property for the chrome plating, and fully satisfies the reqirements.

(3) Corrosion resistance

Good corrosion resistance against chemicals other than chlorides, and is stable in the atmosphere.

(4) Heat resistance

When heated, hydrogen occluded in the coating is released and the hardness lowers. When exceeding 300°C, the hardness rapidly lowers. Therefore, the wear resistance is also decreased.

[Table] Examples of industrial chrome application areas and purposes

Area	Applicable parts	Purposes
Automotive	Crank shafts, Journal, Cams, Cylinder liners, Piston rings, Rods, etc.	Wear resistance, Lubricity, Porosity, Hardness, etc.
Aircraft, Marine vessels	Crank shafts, Journal, Cylinders, Pistons, Rods, etc.	Wear resistance, Buildup, Porosity, Lubricity, etc.
Industrial machinery	Drying cylinders for textile, chemical, food, pharmaceutical, printing applications, Various rolls, spindles, Piston rods, Valves	Wear resistance, Corrosion resistance, Porosity, Non-adhesiveness, Contamination prevention, etc.
Inspection, cutting tools	Files, Micrometers, Ring gauges, Reamers, Taps, Drills, etc.	Non-adhesiveness, Hardness, Wear resistance, Buildup, Cutting ability, etc.
Die and mold	Glass molds, Plastic molds, Various molds	Non-adhesiveness, Wear resistance, Buildup, etc.
Chemical industry	Various tower tanks, Pump shafts, Impellers, Valves, etc.	Corrosion resistance, Wear resistance, etc.

#134 Functional Plating

By システム管理者 on October 12, 2012 12:00 AM | No Comments | No TrackBacks

We have been discussing what are familiar to our normal daily lives such as ornamental and anti-corrosive plating types. From here, we will explain the "Functional Plating" that are needed on products in order to maintain certain functionality.
Before we begin the explanations on Functional Plating, we will give some considerations on the functionalities required for the various products.

[Table] Characteristics required for various products

	Characteristics
	Deco rative ness	Anti- corro sive ness	Anti- wear ness	Mecha nical Prop erty	Elect rical Prop erty	Opti cal Prop erty	Ther mal Prop erty	Physi cal Prop erty	Chemi cal Prop erty	Other Proper ties
Auto motive	○	○	○	○	○	○	○	○	-	○
Bicycle	○	○	-	○	-	-	-	-	-	-
Home Appli ances	○	○	-	-	○	-	○	○	○	○
Audio Equip ment	○	○	-	-	○	○	○	○	-	○
Aircraft	-	○	○	○	○	○	○	○	-	○
Com puters	-	○	-	○	○	-	-	○	-	-
Commu nication Equip ment	-	○	-	○	○	-	-	○	-	-
Office Equip ment	○	○	○	○	○	○	-	○	-	-
Optica Devices	○	○	○	○	-	○	-	○	-	-
General Machi nery	○	○	○	○	-	-	-	○	-	-
Heavy Machi nery	-	○	○	○	○	-	○	○	-	-
Molds	-	○	○	○	-	-	○	○	○	-
Marine Vessel	-	○	○	○	-	-	-	○	○	○
Const ruction	-	○	-	-	-	○	○	-	-	-
Printing Machi nery	-	○	○	○	-	-	-	○	○	-
Medical Equip ment	-	○	○	○	-	-	-	-	-	-
Eye Glasses	○	○	-	-	-	-	-	-	-	-
Sporting Equip ment	○	○	-	-	-	-	-	-	-	-
HVAC	○	○	-	○	-	○	○	-	-	-
Statio nary	○	○	-	-	-	-	-	-	-	-
Lighting	○	○	-	-	-	○	○	-	-	○
Home Hard ware	○	○	-	-	-	-	-	-	○	-
Clocks	○	○	-	-	○	-	-	-	-	-

#133 Tin-Zinc Alloy Plating/Cadmium Plating

By システム管理者 on October 5, 2012 12:00 AM | No Comments | No TrackBacks

（1）Tin-Zinc Alloy Plating

It is said to have excellent corrosion resistance characteristics against salt water and moist atmosphere, especially, tin at 70% supposedly shows the highest corrosion resistance. It has good solderability and can be directly plated on aluminum.
Since tin is more expensive compared to zinc, it will inevitably be more costly. In order to counter this, multiple plating layer methods where conventional zinc plating or chromate treatment are deposited over a several micro-meters of tin-zinc alloy plating are employed.

Fig1

（2）Cadmium Plating

Although this was formally a popular anti-corrosion plating along with zinc plating, the occurrence of Itai-Itai disease from cadmium has caused the shift towards zinc and other plating types.
However, the cadmium plating has exceptional corrosion resistance ability against seawater, and the chromate treatment has good solderability, thus it is still persistently high in demand in aerospace, nautical vessel components, electrical components industries.

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