why don't we go ahead and get started um so just a quick overview of um you know the the agenda for today's talk just gonna give you start off with an overview of what what do we mean by decorative pvd coatings i am going to give a a brief tutorial of how the coatings are made since there's many of you that are beginners and and are new to pvd i thought it'd be good to get everybody level set and then i'll go into some more detail about the types of uh decorative pvd coatings the different materials that are used and how they're made and then i'm going to finish up with a little little discussion about color assessment it's a pretty important topic when you're when you're discussing decorative coatings being able to assess color judge color visually and with instrumentation so i'm going to talk a little bit about some of the best practices and some advice in that area and then of course as as questions come up please feel free to add them to the list and we'll uh cover as many as we can at the end of the talk okay so getting into our overview so the first thing i like to just reinforce is that when we're talking about decorative pvd coatings the important part is the durable we often call them durable decorative pvd because for most applications where these types of coatings are appropriate durability is an important aspect of why they're chosen whether it's for wear resistance needing a hard surface or if it's just for a chemical or corrosion resistance but there's got to be some kind of a driver just beyond looking great it's got to also perform and then when we look into the the types of coatings i like to categorize them in two different ways either as what i'd call natural finishes where we're really trying to represent natural uh alloys golds coppers bronzes where they have these distinct colors where we're using other materials in order to enhance the properties of a coating yet maintain the look of another kind of material and then the other kind of what i like to call artificial finishes and these are ones that may not be quite readily available in nature things like black dark gray graphites blues rainbow colors etc so these are made in little different ways and we're going to go into that a little bit later but just to give you a just a glimpse of how we like to think about these an overview of the markets that we generally work in and that you find these coatings um over here on the left side some of the original areas in which they were introduced especially the jewelry this is where they were really first introduced back in the 80s watches rings and such were really where pvd coatings found their first use as decorative applications then quickly moved into door hardware and plumbing fixtures back in the 90s of course everybody remembers polish brass being quite a popular finish back then and you know zirconium nitride coatings which we'll talk about really became a mainstay in a way to provide lifetime finishes in those industries then moving on sporting goods firearms we're really seeing a a a lot of new work in the firearms starting to embrace decorative pvd coatings i'm moving on to consumer electronics it's uh it's very likely that those smartphones you have in your pocket have some kind of a pvd decorative coating on it and then of course automotive both interior and exterior this isn't a comprehensive list but you know these are where you're going to find uh these coatings most most often okay switching gears how these coatings are made so the majority of these are made by what we call physical vapor deposition or pvd for short this is a method by which we start with a solid material which we often call a target which is represented by this uh this disk on the left side so what we're trying to do is take that solid remove material in the form of atoms or ions or molecules from that source by use of some kind of an energy whether it's a plasma energy or a thermal energy whereby you transport that that material that has been converted into a vapor hence the physical vapor deposition you're in some kind of a controlled medium usually a vacuum chamber backfilled with some kind of gas to control the types of properties you're looking for that material transports from your target through that medium and lands and condenses and reacts on the surface of the substrate so this is the part that you're looking to apply the coating to we call them substrates just for nomenclature but that's those are the main portions of what we mean so you've got a target material energy to transform it convert it to vapor and then it condenses on your parts and this all happens in a large vacuum chamber so this this schematic is a representative uh image of a typical vapor tech system it's a large vacuum chamber vessel that is uh we have a the door open on this one so you can see what's going on inside but this is a controlled environment at a low pressure backed by a number of uh backing pumps but inside let's start at the center so this very um energetic looking device here this is what we call our source or our cathode this is a rod of material or the target that i mentioned in the previous slide this is our starting material it can be really any metal any the only requirement is that it's electrically conductive so we tend to use materials like zirconium or titanium so we're starting with that material we strike an arc on the surface and that arc travels along the length and also around the circumference of that target and where that arc is on the surface it's actually uh vaporizing material and also ionizing material it's ejecting material in 360 degrees around and you have a very high energy of material coming off a mixture of ions which are energetic atoms that have been had an electron removed and that is getting deposited all around the inside of the chamber now on the outside part of the chamber is where you put your parts or your substrates they're mounted on on racks that are mounted onto a carousel and that carousel rotates around the chamber in one axis and then each of those racks also rotates on an independent axis for a second second axis rotation and this allows for a good uniformity of coating coverage on parts as they travel around the circumference of the of the chamber you know one of the nice things about this configuration of having that target material in the center is that it's it's it's depositing material throughout the 360 degrees around the chamber in some configurations you have these sources mounted on the walls which is then spraying material inwards towards the inside of the chamber which is also a good way of doing it we just prefer for most of our applications to spray from the inside out it has a few advantages let's see what else we have in the chamber we have our power supplies that power both the source and we also have power supplies that drive a a bias on these substrates we apply a negative bias voltage on the parts which helps drive the positively charged ions coming off of the target to it which helps drive reactions and densify coatings we're also introducing a number of gases into the chamber and this is how we control the reactions and control the different colors which we'll discuss in more detail later so this is the configuration that we find in all the vapor tech systems we have different sizes of chambers depending on you know the applications the needs for throughput etc okay so i've mentioned cathartic arc cathodic arc is the type of technology that we use in the in that center arc source in the chamber another type of pvd that's commonly used is called magnetron sputtering i'm going to just do a little compare and contrast here just so you can get a little uh idea of the differences here because they're both used and very commonly so the biggest difference is energy cathodic arc is a very high energy process most of the material coming off the target is ionized that's that positively charged aspect that i mentioned before magnetron fairly low energy small amount of ionization there's ways to boost that with various configuration but it's still fairly low that energy helps us drive reactions at low temperatures which is really key for a lot of the applications we work in where we're trying to apply our coatings onto plastics or other temperature sensitive materials whereas in magnetron sputtering sometimes to drive the same reactions you have to use thermal energy you have to heat parts up which a lot of substrates can't accommodate another thing is target poisoning which is essentially a surface effect that happens on your target whereby it reacts with the surrounding material surrounding gases like the oxygen or nitrogen cathodic arc is less sensitive magnetron sputtering is quite a bit more sensitive so this is a lot easier to control the environment in which the coatings grow and react the one drawback with cathodic arc is the amount of defects that are ejected from the process now these are really small liquid droplets that occur because it's such a high energy process the nice thing about decorative coatings is they're so thin that these macro particles really don't play a role they're invisible they don't have any any real effects but in contrast magnetron sputtering has many fewer it's not a no defect but it has much fewer defects than magnitude are then i'm sorry from cathodic arc so due to these reasons on the on the left-hand side you know cathode cork is the preferred method for most of the decorative coatings that we use but they can also be used in conjunction very often you know using them together whether or not making multi-layer coatings or magnetron sputtering is also used for some of the cvd coatings that we're going to talk about later a little some of the diamond-like carbon coatings okay so let's switch gears and talk about the coatings themselves so what i mentioned earlier i talked about the natural coatings the the coatings in which that we are trying to mimic those uh those natural alloys such as the the coppers and brasses and such so these coatings tend to be opaque meaning that they don't transmit um light through them so what you're seeing is the colors that you're seeing are defined by the reflected light of what your com what's coming back to your eyes when you see this and the nice thing about this is that that color is defined by the material properties the compound that you're making the material itself and it doesn't change with thickness so as you're building a thicker coating the color doesn't change you can be very thin coating and get the same color you can be as thin as a tenth of a micron or 100 nanometers but more often or than not our coatings for decorative are tend to be in the quarter to half a micron range as opposed to say thick functional coatings for wear applications which could be many times this thickness because these coatings are opaque it really works well for complex geometries if you have parts with a lot of different features and you want to get a uniform color all over it you really want to work with an opaque coating and again like i mentioned you know these coatings are generally mimicking the look of pure metals and alloys you know for example you know we can match the color of things like gold we may not be able to make them look exactly like gold but it's a good representation and generally unless you're comparing them side by side you're not really going to notice a difference some metals we can match almost exactly stainless steels nickels brasses for example but some some some of the materials like coppers and golds are really really difficult to get an exact match and a lot of that has to do with the electronic structure and the conductivity of those materials that you just can't match with any other materials and really these are the majority of our decorative coatings the other type you know what i was talking before i mentioned artificial coatings which may not be the most natural of looking ones these tend to be made by optical approaches where these coatings can be transparent or they can be semi-transparent meaning that the color is often driven by the thickness if it is a below a critical thickness it can be you can get some interference colors some rainbows or you know some of these vivid colors like these blues vivid blues come from an interference effect but once you get above a certain thickness where all of the light is getting absorbed by the coating and no more is getting reflected from the under surface it will then become opaque but it takes much thicker layer before it becomes opaque sometimes as often as a micron thick and this is common for things like metal oxides and diamond like carbons dlcs and those those are good examples of those so let's talk a little bit about the starting materials we use what are we using to make these coatings so when we talk about the metals or the substrates we have three main metals that we work with it's not exclusive to these like i said any any uh any metal can be used but in order to form the types of coatings that are most commonly used we use these big threes zirconium titanium and chromium and by far zirconium is the most popular and we'll talk more about that and then reactive gases we use uh gas very common industrial gas is nitrogen oxygen methane acetylene these are very common uh inexpensive gases easy to acquire and between these seven just these seven ingredients almost every single coating we talk about can be made so speaking of these materials and these reactions i've mentioned what class of materials are we talking about so um we're talking about nitrides carbon nitrites oxycarbides all sorts of different compounds and so the properties they have and how we describe them often they have very ceramic-like properties but you know traditionally ceramics are you know hard and brittle and insulating these materials generally are hard and brittle but they're also very conductive so they're more like uh ceramic-like cermets which is kind of a hybrid between metal and ceramic you know hardness can be as high as 10 times as hard as the base metal good example is titanium titanium metal itself very soft titanium nitride extremely hard and like i said most of these do remain electrically conductive which allows them to retain their reflectivity and their shiny nature to mimic metals and typically these types of compounds are going to be more chemically inert than the base metal they started with you know titanium oxide titanium nitride is going to be more inert than a titanium metal for example okay so let's let's talk about each of these individually so let's talk about zirconium first like i said this is the one that we use most often by far more than any other base you know 14 of the standard vapor tech finishes are based on this i think we have on the order of 20 or 22 standard ones so so two-thirds of them are based on zirconium and this this material not only can you make a lot of colors it also has the best chemical and corrosion resistance it's just a really durable metal it's very stable in a wide range of environments and against various chemicals so the types of coatings again these kind of compounds we talked about before the nitrites carbon nitrides wide range of different colors anything from the brasses and nickels to the you start adding uh some carbon you start getting some of the redder redder yellow metals from the gold's bronzes we're going to talk a little more about our oxycarbides which is a unique coating family where we get some of our blacks and graphites and then zirconium oxides where we get some things like some stainless steels and blues so just an example of how we can use the same compound but get wildly different colors so let's talk about zirconium nitride widely used to make colors such as nickel and brass so this is a little bit simplistic but basically if you have a low amount of nitrogen that you're introducing into your chamber you can form more of just a pale nickel uh pale yellow nickel color however if you add a lot of nitrogen and you you know fully react your zirconium with nitrogen it looks just like brass and you know there's the 0.2 here just basically indicates that you don't have it fully reacted this is where you have perhaps a solid solution of nitrogen in with the zirconium it's uh it's still going to be much much harder than pure zirconium however because it's not fully reacted it doesn't have as much of the ceramic like qualities and it's not going to be quite as hard as something that's fully reacted like a a brass colored zirconium nitride still going to have a lot of great properties but just a little different and we can change between these colors and you can get anything in between just by modulating the amount of nitrogen that you're introducing in the chamber and very similarly nitrogen and carbon gases you get carbon nitrides and there are two carbon gases we use most often methane and acetylene um you know they can often be used interchangeably but just in this this quick example sometimes you just get different shades of colors and we tend to get a little bit more red when we start using acetylene than we do with methane so you get some more of the rose gold colors however with methane tends to be what we call a cleaner gas or more thermally stable so it tends to be a little bit of an easier process to control however acetylene can give us a you know different a little bit of a different color palette as needed and this is one zirconium oxycarbides are like what we what we like to call them z-rock that's our internal name for it this is a this is a family materials that we patented patented um quite a while ago but so this is a unique uh family of of materials at vaportec and we can get a wide variety of different colors with this material so these these are in the range of those optical coatings that we were talking about and we can get a variety of shades just by modulating the amount of oxygen and carbon in these gases anything from a kind of a dark gray that we call graphite or we can even go into what we call a true black which is a very dark neutral black color and then within each of these graphite and true blacks we have ways in which we can modulate it to the blue side of things and make things that we call cool which is maybe has a little bit of a blue tint uh make a blue black for example or we can go in the other direction and go into more warm colors where there might be more of a yellowish or red tones where we get a warm graphite so we've got a wide range of different types of colors that we can achieve just with this one material switching gears to titanium this one's like like i think believe i mentioned earlier the longest history of use is a decorative coating this is where some of the original work was done back in the 80s you're probably very familiar with the work that it's done in functional coatings on you know tool coatings and such very similar as zirconium as far as the types of reactions that occur tends not to have as wide of a color palette so it doesn't get used as often and it's not quite as stable with chemicals or corrosion but you can get a lot of the golds and rose golds and bronzes with titanium as well and then there's chromium chromium um you know generally shades of gray and silver um it doesn't have any of the yellows and reds that you get with the titaniums and the zirconiums however you can get some really nice colors that are very attractive chrome is very commonly used in electroplating we have a way in which we can mimic that same finish with a pvd clean pvd process you get silver or aluminum type color stainless steels going into the dark grays and blacks and then i do want to mention a little bit about diamond light carbon dlcs this has really been growing over the last few years high demand for use as a decorative coating and this is an example of what it generally looks like we see it quite often on in sporting goods with golf clubs um it's a it's a very durable coating it's got one of the characteristics of it it's got very low friction which means that you know even though it might not be as hard as some of the other coatings just because it's got low friction it really helps hold up against a lot of abrasive wear not a lot of different colors you can get really just dark grays into maybe some of the black colors some limitations is that it's it is a thicker coating because it's an optical coating you have to be above a certain thickness before it becomes opaque and also requires some higher temperature processing so you don't really see this one applied on plastics and such it's really limited to metallic substrates there are a few ways to do this one of which we have not talked about yet which is uh plasma enhanced chemical vapor deposition or sometimes plasma assisted chemical vapor edition vapor deposition or pe cvd which is a method in which we use acetylene gas or methane gas break it down with a plasma and form a coating based on that or you can also use sputtering starting with a metal material very commonly tungsten could also use chromium where you're sputtering metals like tungsten in a settling environment and you can form these tungsten dlcs they go by a lot of different names wdlc wcc they're generally the same thing but just different nomenclatures you might come across okay so i know we have only got a few more minutes here but um you know this is a topic that's uh really quite important as we talk about decorative coatings and i think we could probably have an entire webinar on this topic by itself but i just want to go over some of the some of the some of the high level aspects of it that are important takeaways i think for for this audience first of all um color is something that we can actually measure it's of course it's very subjective it's something that you know we look at something with our eyes but of course in in the engineering world in scientific world we like to be able to put a number to things we like to measure it and we measure things by use of a spectrophotometer which is an instrument that essentially shines a light on an object and then looks back at the light reflecting back and it identifies a coordinate of color that lands within this 3d spherical representation of all the colors available so this is also called the c lab color space model let me just walk you through how this is laid out so the l is the typically what this i guess the y axis which is the white to black so something that is a fully white would have a l of 100 percent and something that is completely black and non-reflective would be a zero then as you're looking at the color hues you have the a component which is the red and green axis so as you start with a negative a you're on the green spectrum and then as you move to a positive red a positive a you get into the reds and very much the same way with the b which is the yellow blue axis as you are at a negative b you are in the blue and then as you move towards the positive b you are into the yellow another concept that you will often see if you're looking if you're talking with people about color space and color numbers is a delta e value and this delta e value is essentially when you're comparing two colors how far apart are they within this color space and this is often used when you have a target color or you know what you're trying to achieve and then what you actually get so if you have from your quality control for a certain color you're you're shooting for a certain color and you always want to know well how far away am i and you just use this nice equation which is basically just the distance in a 3d space between parts so you just take the difference of each each of the components from your target square it and then you sum it up and then you take the square root and you get a number and the larger that number is the further apart they are in that space and that's a way you can gauge how far away from your target you are and just as an example if you've never seen a spectrophotometer before this is just a handheld model in this picture different versions of it most of what we use are handheld they're also bench top models but this is just one that works and let's say we're taking a picture of this yellow piece it's going to spit out a number for example it's it's got some it's got a high value of l which means it's fairly reflective and bright it's got a little bit of red in it which means it's got a a value and of course it's very yellow so it's got a very high b value and of course that'll land somewhere in this spectrum here so just an idea of how that works so color measurement one of the things we always like to warn people about is it's very valid on flat surfaces but we always caution people in trying to use it on complex geometries due to curvature of surfaces it can also often throw off the values or introduce more noise um and also surface texture if you've got a brush texture or something like that it can also throw off your measured values and so you have to be really cautious about that um for production control we often recommend um that our customers implement using witness coupons and what do i mean by that they're basically just little little pieces of metal usually stainless steel that you'll include in each of your runs it's a controlled surface that's always the same every time i put that in the chamber along with the parts you're coding when you take it out you shoot the number and then you can plot it on a statistical process control chart which is just a really nice way of being able to monitor the performance of your system and making sure that everything is in control it's a little bit harder to do with visual assessment because again that is very subjective however we always like to use data to drive our processes and control them and one last thing i'd like to talk on my last couple minutes here is just about color judgment in particular visual assessment now we've been talking about instrumentation very important however at the end of the day it's really how it looks to our eyes and ultimately passing and failing components that have decorative coatings generally falls in on you know at some point you have to do some visual assessment and often our customers will use visual standards meaning it's a a either a range of sample parts or sample coupons that are representing the range highest range at which it's acceptable for color variation so often a light sample in a dark sample you would take apart out of the chamber look at it and see whether or not it falls between those standards again it's really important the environment at which you do these judgments we tend to use light boxes recommend light boxes which are controlled areas where there's controlled light neutral colors within you can whether or not you want to have daylight or fluorescent lighting you can control the light because that has a big influence on how you perceive the color of a surface and then another thing is you really want to make sure if people are doing this visually that your inspectors are qualified a big issue is colorblindness um one out of every 12 men have some degree of colorblindness one out of every 200 for women one of the ways in which this is evaluated is this ishihara test which is uh you've probably seen these before but a a collection of colored dots and you're looking to see if you can distinguish the number within um you know there's standardized books on this but i found there's also free apps for your phone that you could just download and do a quick test it's probably not the best official test but if you want to get an idea of whether or not you've got a deficiency or your inspectors have a deficiency it's probably a good first pass very similar to color blindness is the ability to distinguish between hues and this is the farnsworth munsel test that we also recommend and this is just a series of little pellets that have varying shades of color on them and the idea is you start these out mixed up and you are um to put them in order of graduations of color so if you can put them back in order in the right right order that means that you are good at being able to distinguish very fine changes in color hue so both very very uh useful tests to assess uh your your inspectors one last thing i want to say and it's been a very important learning over my 20 years of working in in decorative coatings is how important the influence of surface texture has on color mismatch and judgment i can't stress this enough and you know one thing we haven't really talked about is that you know these coatings are so thin they can apply be applied on any kind of of texture so whether it's brushed or a matte texture um and we don't really change the they're thin enough that they don't really change the texture however those textures can have a huge impact on the way you perceive color for example if you were to apply the same put the same parts in the chamber apply the same color on something that's highly polished versus something that's got a matte surface the polished surface is going to look much darker than that that has a matte or a diffuse surface and that has to do with the diffusion of light and what's getting reflected back to your eyes and it can be very tricky if you're if you're trying to judge parts that you may have different texture if you've got different suppliers vendors providing too much variety and texture that can really throw off throw off your color so um just a just a just a word of kind of a pro tip from here just be very cautious of that when you're when you're judging color you